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UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


BULLETIN  No.  268 


THE  SUNFLOWER  AS  A  SILAGE  CROP 

COMPOSITION  AND  YIELD  AT  DIFFERENT  STAGES 
OF  MATURITY 

BY  W.  L.  GAINES  AND  W.  B.  NEVENS 


URBANA,  ILLINOIS,  JUNE,  1925 


CONTENTS 

PAGE 

INTRODUCTION 407 

OBJECTS  OF  THE  STUDY 408 

PLAN  OF  INVESTIGATION 408 

RESULTS  SECURED 411 

Yield  of  Crop  and  Constituents 411 

Mathematical  Expression  of  Growth 415 

Growth  in  Stalk  of  Sunflower  and  Corn 418 

Growth  in  Seed  of  Sunflower  and  Ear  of  Corn 421 

Significance  of  the  Growth  Constants 426 

Composition  of  Crop 429 

Yield  and  Composition  of  Crop  as  Ensiled 429 

Comparative  Yields  of  Sunflowers  and  Corn 434 

Yield  of  Crop  in  Terms  of  Digestible  Nutrients 435 

Fertility  Relationships 436 

Thickness  of  Planting 442 

Time   of    Planting 443 

SUMMARY  AND   CONCLUSIONS 445 

REVIEW  OF  LITERATURE 447 

Investigations  Dealing  with  Composition  or  Yield  of  Sunflowers 447 

Crops  Other  Than  Sunflower:    Studies  of  Composition,  Yield,  or  Feeding  Value, 

at  Different  Stages  of  Growth 449 

Conclusions  from  Review  of  Literature 452 

LITERATURE  CITED..  ..454 


THE  SUNFLOWER  AS  A  SILAGE  CROP 

COMPOSITION  AND  YIELD  AT  DIFFERENT  STAGES  OF  MATURITY 

By  W.  L.  GAINES,  Chief  in  Milk  Production,  and 
VV.  B.  NEVENS,  Assistant  Chief  in  Dairy  Cattle  Feeding 

INTRODUCTION 

A  widespread  interest  in  the  possibilities  of  the  sunflower  plant  as 
a  practicable  crop  has  been  aroused  in  sections  of  this  and  other  coun- 
tries where  the  plant  has  not  previously  been  grown  on  a  commercial 
scale.  This  interest  has  been  occasioned  largely  by  the  possibility  of 
the  substitution  of  sunflowers  for  corn  as  a  silage  crop,  particularly  in 
those  sections  in  which  corn  does  not  grow  satisfactorily  on  account  of 
climatic  factors  or  the  attacks  of  insect  pests. 

The  utilization  of  sunflowers  for  silage  in  Illinois  has  not  been 
attended,  up  to  the  present,  with  a  full  measure  of  success.  Several 
problems  have  arisen  with  regard  to  the  keeping  qualities  of  the  silage 
and  with  respect  to  its  value  as  a  feed  for  livestock,  particularly  dairy 
cows.  Furthermore,  there  has  been  a  variance  in  recommendations  and 
in  practice  with  respect  to  the  methods  of  culture  and  to  the  time  of 
harvest. 

It  is  obvious  that  any  crop  which  shall  hold  an  important  place 
in  the  cropping  system  of  a  livestock  farm  must  make  some  important 
contribution  to  the  income  of  the  farm,  either  as  a  cash  crop  or  as  a 
crop  yielding  a  large  amount  of  feed  per  acre.  Among  the  questions 
which  naturally  arise  in  connection  with  the  use  of  sunflowers  as  a 
silage  crop  are  those  regarding  the  methods  of  culture  and  stage  of 
growth  at  which  the  crop  should  be  harvested  in  order  to  give  the  maxi- 
mum returns  in  feeding  value  per  acre. 

From  a  survey  of  the  literature  on  this  subject  it  was  concluded 
that  the  lack  of  concordance  in  the  results  of  sunflower  silage  tests 
reported  by  different  experiment  stations  and  individuals  might  be  due 
to  the  fact  that  the  sunflowers  were  ensiled  at  such  widely  differing  stages 
of  growth  that  the  character  of  the  silage  used  in  some  trials  was  very 
different  from  that  used  in  others.  Accordingly,  an  investigation  was 
planned  which  it  was  hoped  would  solve  some  of  the  problems  involved. 

A  study  of  the  composition  and  yield  of  the  crop  at  different  stages 
of  development  seemed  essential  to  the  determination  of  the  stage  at 
which  the  crop  should  be  harvested  in  order  to  secure  the  maximum 
feeding  value  per  acre.  Such  a  study  was  therefore  carried  out  as  de- 

407 


408  BULLETIN  No.  268  \_June, 

scribed  in  this  bulletin.  But  since  the  chemical  composition  of  the  crop 
gives  relatively  little  indication  of  the  feeding  value  of  the  silage  made 
from  the  crop,  particularly  as  regards  digestibility,  palatability,  and 
physiological  effects,  a  study  of  these  factors  in  the  silage  produced 
from  sunflowers  harvested  at  different  stages  of  maturity  was  also 
undertaken  as  a  necessary  phase  of  the  project. 

The  results  obtained  in  the  study  of  the  feeding  value,  composition, 
and  digestibility  of  the  silage  are  published  in  Bulletin  253  of  this 
Station.  The  results  of  the  study  of  the  composition  and  yield  of  the 
sunflower  crop  at  different  stages  of  development  are  reported  here- 
with. The  results  obtained  in  one  season  and  on  one  field  may,  of 
course,  not  be  duplicated  under  other  conditions  of  season  and  soil. 

OBJECTS  OF  THE  STUDY 

This  investigation  was  undertaken  for  the  purpose  of  securing  in- 
formation on  the  following  points: 

1.  The  yield  per  acre  of  the  sunflower  crop  in  stalk*  and  seed  at 
different  stages  of  maturity,  including  the  yield  of  the  feed  nutrients 
of  the  crop  as  commonly  distinguished:   namely,  dry  matter,  protein, 
fat,  crude  fiber,  and  nitrogen-free  extract,  the  ash  being  further  consid- 
ered in  some  cases  as  to  several  of  its  elements,  namely,  aluminum, 
calcium,  iron,  magnesium,  phosphorus,  potassium,  sodium,  and  sulfur. 

2.  The  percentage  composition  of  the  crop,  data  on  this  point  being 
of  course  essential  to  the  yield  estimates. 

3.  The  effect  of  time  and  rate  of  planting  on  yield  and  composi- 
tion of  the  crop. 

4.  From  the  foregoing  to  ascertain  if  possible:    (a)   the  state  of 
maturity  at  which  it  is  best  to  harvest  the  sunflower  crop  for  silage; 
(b)  the  best  time  and  rate  of  planting  for  silage;  and  (c)  the  amount 
and  kind  of  fertility  removed  in  the  crop. 

PLAN  OF  INVESTIGATION 

A  field  of  the  Station  farm  at  Urbana  was  utilized  in  growing  the 
crop.  The  field,  which  had  been  subjected  in  previous  years  to  quite 
heavy  grain  cropping,  was  about  40  by  80  rods  in  size  and  fajrly  uniform 
as  to  soil  (Fig.  1).  The  Mammoth  Russian  variety  of  sunflower 
(striped  seed)  was  used.  There  was  some  slight  mixture  of  a  multi- 
headed  variety. 

The  main  portion  of  the  crop  was  planted  May  18,  1921,  in  rows 
3.38  feet  apart  and  developed  an  average  stand  of  one  plant  to  10.55 
inches  (14,662  plants  to  the  acre).  Three  silos  were  filled  from  this 

"The  term  "stalk"  is  used  to  refer  to  the  entire  portion  of  the  plant  harvested, 
except  the  seed. 


1925] 


THE  SUNFLOWER  AS  A  SILAGE  CROP 


409 


main  crop,  one  on  August  13,  another  on  September  2,  and  a  third  on 
September  21.  The  crop  as  harvested  was  weighed  and  sampled,  and 
the  samples  analyzed.  The  resulting  silage  was  later  fed  in  comparison 
with  corn  silage.  Bulletin  253  describes  the  way  in  which  the  analyses 
were  made  and  the  digestion  trials  conducted.  The  results  from  the 
crop  harvested  as  silage  gave  data  at  three  stages  of  growth,  on  differ- 
ent but  comparable  soil  areas. 

A  further  analytical  study  of  the  main  crop  was  made  from  field 
samples  taken  at  random  at  ten-  or  eleven-day  intervals  thru  the  grow- 
ing period  of  the  crop,  after  it  had  reached  a  height  of  four  or  five  feet. 
For  this  purpose  four  consecutive  rows  (about  eighty  rods  in  length) 
near  the  middle  of  the  main  crop  field  were  reserved.  Samples  were 
taken  65,  75,  86,  96,  106,  117,  127,  and  138  days  after  planting.  In 


FIG.  1. — GENERAL  VIEW  OF  SUNFLOWER  FIELD 

This  view  gives  a  general  idea  of  the  field  and  the  appearance  of  the  crop  at  an 
early  stage  of  growth,  49  days  after  planting.  The  field  samples  were  taken  from  the 
center  4  rows  starting  16  days  later.  (Corn  at  the  extreme  right.) 

selecting  the  plants  for  a  sample,  the  first  plant  was  taken  at  a  pre- 
selected number  from  one  end  of  a  row,  this  number  being  different  at 
each  sampling  period.  From  this  plant  as  a  starting  point  every  one- 
hundredth  plant  was  taken  at  the  first  sampling  period,  every  ninety- 
ninth  plant  at  the  second  period,  every  ninety-eighth  plant  at  the  third 
period,  and  so  on  down  to  the  eighth  and  last  period.  This  method  of 
selecting  the  plants  in  the  field  was  intended  to  give  a  random  sample. 
The  samples  consisted  of  about  sixty  plants  each. 

The  .selected  plants  were  cut  six  inches  above  the  ground;  the 
number  of  plants  and  their  combined  weight  determined;  the  seeds 
separated  (except  at  65  and  75  days,  when  the  seeds  were  not  sufficiently 
formed);  the  seeds  weighed  and  sampled;  the  stalk  portion  reweighed, 
cut  with  a  power  feed  cutter,  and  sampled  by  the  method  of  quartering. 
The  subsamples  of  stalk  and  seed  thus  obtained  were  oven-dried  at 


410  BULLETIN  No.  268  [June, 

45-50°  C,  ground  to  pass  a  one-millimeter  sieve,  and  preserved  in  glass 
jars  for  analysis.* 

Analytical  Methods  Employed  in  the  Analysis  of  Sunflower  Seeds  and  Resi- 
dues."— "Owing  to  the  difficulties  involved  in  determining  iron  and  aluminum  in  the 
presence  of  phosphates,  it  is  desirable  to  explain  briefly  the  methods  used  in  obtaining 
the  analytical  results  herein  reported. 

"The  ashing  was  carried  out  in  platinum  dishes  to  avoid  the  contamination  in 
the  glaze  of  porcelain  dishes  due  to  the  presence  of  phosphates.  In  each  case  when 
new  material  was  needed  for  analysis  the  percentage  of  ash  was  determined,  so  that 
the  percentages  of  the  various  elements  in  the  material  would  not  be  disturbed  be- 
cause of  the  presence  of  varying  amounts  of  unburned  carbon.0 

"In  each  determination  one-half  gram  of  material  was  used.  Solution  of  the  ash 
was  obtained  by  using  5  cc.  of  nitric  acid,  Sp.  G.  1.42,  and  hydrochloric  acid,  Sp.  G. 
1.19,  diluted  to  20  cc.  This  was  evaporated  to  dryness  in  a  platinum  dish,  filtered,  and 
the  same  dilution  noted  above  was  added.  The  phosphorus  was  then  removed  and  the 
iron  and  aluminum  determined  according  to  the  method  of  Krug;27  see  also  L.  A.  Cong- 
don  and  J.  A.  Carter.13  Briefly,  this  method  removed  phosphorus  as  ammonium  phos- 
phomolybdate.  It  was  washed  with  ammonium  nitrate  water  and  the  iron  and  aluminum 
was  precipitated  in  the  filtrate  with  ammonia  in  slight  excess  and  as  cool  as  possible. 
Boiling  has  a  tendency  to  precipitate  white  molybdic  oxid.  The  precipitate  of  iron  and 
aluminum  was  redissolved  in  nitric  acid  and  reprecipitated  as  above,  a  procedure  which 
insured  no  contamination  by  molybdic  oxid.d 

"The  calcium  was  determined  in  the  filtrate  from  the  iron  and  aluminum  in  the 
usual  way,  with  ammonium  oxalate,  and  burned  to  calcium  oxid,  except  that  the  am- 
monium oxalate  was  added  in  the  cold  to  an  acid  solution  instead  of  to  the  usual 
•ammoniacal  solution.  The  ammonia  was  then  added  in  the  cold,  slightly  warmed,  and 
allowed  to  settle  until  the  next  working  day. 

"This  procedure  naturally  produced  a  fine  crystalline  precipitate  and  it  was  neces- 
sary to  use  the  best  grade  of  filter  papers  in  order  to  obtain  a  clear  filtrate. 

"Magnesia  was  determined  in  the  filtrate  from  the  calcium  determination  in  the 
usual  way. 

"The  alkalies  were  separated  in  platinum  by  means  of  platinum  chlorid.  Solution 
was  effected  with  hydrochloric  acid,  and  barium  hydroxid  was  used  to  remove  mag- 
nesium in  purifying  the  combined  chlorids." 

Adjoining  the  main  crop,  at  the  same  date  (May  18,  1921),  were 
planted  eight  rows  intended  as  thin  planting  and  eight  rows  intended 
as  thick  planting.  The  rows  thickly  planted  developed  stands  averag- 
ing one  plant  to  9.79  inches  and  those  thinly  planted,  one  plant  to  13.21 
inches. 


*Analyses  of  the  feed  nutrients  were  made  under  the  direction  of  Dr.  O.  R.  Over- 
man of  the  Division  of  Dairy  Chemistry  of  the  University  of  Illinois.  The  methods  of 
analysis  prescribed  by  the  Association  of  Official  Agricultural  Chemists  were  followed. 

"The  analyses  of  the  ash  and  this  statement  concerning  them,  were  made  by  J. 
M.  Lindgren,  Chemist,  Division  of  Applied  Chemistry,  University  of  Illinois. 

c"The  true  ash  in  each  case  was  not  determined,  as  some  carbon  always  remained 
in  the  ash.  This  was  necessary  in  order  to  conform  with  considerable  work  done  previ- 
ous to  the  analysis  of  the  ash,  so  as  to  conserve  the  alkalies." 

AUTHOR'S  NOTE. — The  samples  of  the  sunflower  plants  and  seeds  were  ground 
in  a  steel  mill  equipped  with  hard  steel  grinding  plates.  The  possible  contamination 
of  the  samples  by  iron  due  to  this  procedure  was  not  determined,  altho  in  view  of  the 
large  amount  of  iron  present  in  the  samples  the  contamination,  if  any,  is  believed  to 
be  relatively  small. 


/925]  THE  SUNFLOWER  AS  A  SILAGE  CROP  411 

A  second  planting  of  four  rows  was  made  on  June  8,  which  devel- 
oped an  average  stand  of  one  plant  to  10.02  inches.  This  planting  was 
severely  attacked  by  rust,  with  the  result  that  the  yield  was  greatly 
decreased. 

A  third  planting  of  four  rows  was  made  on  June  29.  A  very  poor 
stand,  one  plant  to  17.85  inches,  resulted,  owing  to  dry  weather  at  time 
of  planting. 

A  fourth  planting  was  made  on  July  20.  This  planting  developed  a 
stand  of  one  plant  to  9.53  inches. 

Yields  of  the  "thick"  and  "thin"  plantings  were  determined  by 
harvesting  part  or  all  of  the  crop  for  silage.  Yields  of  the  late  plantings 
were  determined  by  the  method  of  random  sampling  outlined  above. 

RESULTS  SECURED 

We  may  consider  first  the  results  with  respect  to  acre  yields  of  the 
main  crop  as  indicated  by  the  field  samples.  Percentage  composition 
of  the  crop  is  the  result  of  the  quantitative  growth  relations  of  the 
plant,  and  while  the  qualitative  data  must  be  obtained  before  the 
quantitative  estimates  can  be  made,  the  qualitative  changes  are  the  re- 
sult rather  than  the  cause  of  the  quantitative  relations.  The  qualita- 
tive results  may  therefore  be  logically  considered  after  the  quantitative 
results. 

YIELDS  OF  CROP  AND  CONSTITUENTS 

Table  1  shows  the  estimated  yields  per  acre  of  the  crop  as  a  whole 
and  of  certain  of  its  constituents  as  estimated  from  the  field  samples. 
The  data  represent  the  averages  per  plant  of  the  corresponding  field 
sample  multiplied  by  14,662  (the  number  of  plants  per  acre).  In  the 
samples  taken  65  and  75  days  after  planting,  the  seeds  were  not  de- 
veloped at  all,  or  not  developed  sufficiently  to  permit  separating  them. 
From  later  samples  the  seeds  were  separated  and  the  data  for  the  crop 
are  the  sum  of  the  estimates  for  stalk  and  seed  as  separately  determined. 
Eighty-six  days  after  planting,  the  total  quantity  of  seed  obtained  from 
the  60  plants  constituting  the  field  sample  was  insufficient  to  permit 
an  ash  analysis. 

The  plants  which  were  to  constitute  the  last  two  field  samples  were 
selected  on  September  12,  and  cheesecloth  tied  about  their  heads  at 
that  time  in  order  to  prevent  loss  of  seed  by  shattering  or  the  depreda- 
tions of  birds. 

Data  from  Table  1  are  shown  graphically  in  Figs.  2  and  3.  The 
highest  yield  of  crop  is  indicated  at  86  days  (Fig.  2),  August  12,  after 
which  the  green  weight  falls  off  quite  rapidly,  especially  after  117  days, 
September  12.  This  decrease  in  green  weight  is  largely  due  to  loss  of 
water,  as  shown  by  the  fact  that  the  dry  matter  of  the  crop  increases 
up  to  117  days.  After  117  days  there  is  a  considerable  decrease  in  dry 
matter  of  the  crop  as  a  whole.  The  dry  matter  in  the  seed,  however, 


412 


BULLETIN  No.  268 


[June, 


IOP:  ESTIMATED  FROM  SAMPLES  TAKEN  IN  THE  FIELD  AT  INTERVALS  AS  INDICATED 
ds  per  acre  for  the  crop  and  certain  of  its  constituents 

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TABLE  1.  —  GROWTH  OF  THE  SUNFLOWER  C 
Expressed  in  yiel 

a'pnj^ 

mo       —  —  «  fn       m  NO  ON       in—  -NO       O  —  —       Tf^oor*1!       cnfnNO 
m  -iJ1      in      in      in      »n      M-—  ^in      ^CMNO      m*—  tn      rMCM-^ 

J3UEUI  XjQ 

Ccs      f>  oc  —  ^      t^  •<*•  —•      —  .  *—  in      -^  O  -^      ONOI^      cnl^  O 
oc  —  t      oo      ON      oo-*i«m      NO  ON  CM      ON  rn  cs      Tf  CM  NO      in  •»*•  O 

J3JEM 

t^oo      t^«nO      «*"*oo      NO'J'O      i^o^      NCm—  <      inNO—i 
-rt^      ON  O  O      O  CN  CN      Tft^-cM      NO«OON      -^inO      t^-  NO  •^< 
O  oo      CNinin      ooinm      cMmNC      oc  oc  NO      ooin^r      NOCMON 

mNO        ^1        *^        O  —  CS        00  CM  O        ^t«*^NO        —  '        CM        T*        •* 
CMCM        mmmmcMmcMCM*^*— 

J3JJBU1 

HS3JJ 

•^  ^*       en  NO  CN       in  in  O       ONI^NO       cMroin      moo»—  *       CMOOO 
in  Q      r^  oc  *^      r^  f^  <-H      in  oo  •<*•      •—  rn  «*      in*^r^      *—  mm 
oco      ocin-f      NOOr^      oc  (M  »—  i      oc*—  ON      CMOCO      CM^-ON 

^^^^.^^.^^^^               „. 

"Nitrogen-free  extract 

dOJD  JO  UBJ 

"o"o     S-J-p"o     ^"-TJ"H     ^'-^"5     rj-^"^     =2-j~o     d-ri'o 
jSJS    c/5cniS    t«c«;S    c/5"3^    c«c/2^    toc^.5    t«c«.S 

SunuB|d 

UIOJJ  SABQ 

inin      NONO          NO  NO          NO  NO          r^r^          r^r^          oooo 
NOr^      oooo           C^  ON           OO           *—  *—           CMCM           mm 

uei'wa 

CM*^        CMCM              fMCM              —  —  <              CMCM              CMCM              m  m 
CM    1         *-—              CMCM                 1      1                —  —              CMCM                 1     1 

t  OO         II               il             ON  ON              1     '               '     1             OO 
t^            OOOO            OOOO                                ONON            ONON            —  — 

•°N  'iduieg 

*—  CM        t«T.J«              NOt^              OOON              —CM              NOI-^              —CM 
CMCM              CMCM              mm 

7925] 


THE  SUNFLOWER  AS  A  SILAGE  CROP 


413 


continues  to  increase  thruout  the  period.  The  graph  gives  an  idea  of 
the  distribution  of  dry  matter  between  seed  and  stalk.  The  porportion 
of  dry  matter  in  the  seed  increases  thruout,  but  at  the  point  of  high- 
est dry-matter  yield,  117  days,  there  is  less  than  one-fifth  as  much  dry 


40000  • 


Growth  or 
Sunflower  Crop 


Be          9e          toe  m 

Days  of+er  Plan-ting 


'27 


/36 


FIG.  2. — GROSS  FEATURES  OF  THE  GROWTH 

OF  THE  SUNFLOWER  CROP 

Showing   dry   matter  in   the  seed,   dry   matter   in   the   crop 
(including  seed),  and  green  weight  of  the  c/op. 

matter  in  the  seed  as  in  the  stalk.  In  a  comparable  crop  of  corn  grown 
for  silage  during  the  same  season,  the  dry  matter  in  the  grain  was  equal 
to  about  one-half  that  in  the  stalk.  (Table  8.) 

Fig.  3  shows  the  chief  organic  constituents  (from  a  feeding  stand- 
point) of  the  dry  matter;  namely,  nitrogen-free  extract,  crude  fiber,, 
protein,  and  fat.  There  are  relatively  large  amounts  of  nitrogen-free 
extract  and  crude  fiber  and  small  amounts  of  protein  and  fat. 


414 


BULLETIN  No.  268 


[fune, 


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1925~\  THE  SUNFLOWER  AS  A  SILAGE  CROP  415 

So  far  as  the  stalk  is  concerned  there  is  evident  a  pronounced  dis- 
position toward  an  accumulation  of  material  up  to  96  days  and  a  loss 
of  material  after  that  time,  except  as  to  crude  fiber.  This  period  of 
loss  marks  the  period  of  development  of  the  seed,  a  loss  presumably 
associated  with  this  development. 

In  the  case  of  the  seed  there  is  a  variable  rate  of  increase  thruout, 
except  as  to  nitrogen-free  extract.  The  increase  in  fat  is  the  most 
striking  of  the  changes.  Fat  is  the  chief  storage  product  of  the  sun- 
flower seed,  and  the  decrease  in  the  amount  of  nitrogen-free  extract 
is  probably  due  to  its  use  in  the  formation  of  fat  in  the  maturing  seed. 

Ash,  as  may  be  seen  from  Table  1,  shows  the  same  general  relation 
as  the  organic  constituents  in  its  quantitative  changes — that  is,  in  the 
stalk  an  increase  followed  by  a  decrease  and  in  the  seed  an  increase 
thruout.  The  same  relation  holds  also  with  respect  to  the  constituents 
of  the  ash,  except  in  the  case  of  aluminum  in  the  stalk  which,  like  the 
crude  fiber  in  the  stalk,  continues  to  increase  thruout. 

The  crude  fiber  and  aluminum  of  the  stalk  seem  to  perform  differ- 
ently from  the  other  stalk  constituents.  The  crude  fiber  represents, 
from  the  standpoint  of  the  plant,  a  structural  material  which  is  neces- 
sary to  maintain  both  the  form  and  position  of  the  plant  and  is  not 
readily  utilized  for  the  formation  of  the  constituents  of  the  seed.  In  a 
way,  the  crude  fiber  of  the  stalk  is  the  most  representative  constituent 
of  the  plant  which  may  be  used  to  describe  its  growth  as  a  physiological 
process.  The  growth  curve  of  crude  fiber  in  the  stalk  (Fig.  3)  bears  a 
general  resemblance  to  the  typical  growth  curves  of  annual  plants  and  of 
animals.  The  same  may  be  said  of  the  aluminum  of  the  stalk  and  of 
the  various  constituents  of  the  seed  (except  nitrogen-free  extract). 
While  the  present  work  was  not  undertaken  as  a  physiological  study  of 
plant  growth,  nevertheless  the  production  of  farm  crops  is  basically  a 
problem  of  the  physiology  of  plant  growth,  and  this  fact  may  justify  an 
analysis  of  the  data  of  Table  1  on  the  basis  of  one  interpretation 
(Robertson's)  of  growth. 

MATHEMATICAL  EXPRESSION  OF  GROWTH 

Robertson*3  in  his  studies  of  growth,  has  used  and  attached  much 
significance  to  the  following  equation  as  descriptive  of  growth  phe- 
nomena: 

log-—     -— K(t-.tJ  (1) 

A  —  x 

in  which  x  and  t  are  the  variables,  x  being  the  growth  accomplished 
at  any  time,  t;  A  is  a  constant  and  represents  the  value  of  x  at  the 
completion  of  the  growth  cycle;  t^  is  a  constant  and  equals  t  when  x 
equals  %  A;  and  K  is  a  constant.  The  equation  has  the  invariable 
property  of  symmetry  of  its  curve  about  the  point  of  its  intersection 
with  the  ordinate  at  t=ta,  as  a  center.  Up  to  this  point  the  curve  is 
convex  to  the  base,  and  to  the  right  of  this  point  it  is  concave  to  the 


416 


BULLETIN  No.  268 


{.June, 


1925] 


THE  SUNFLOWER  AS  A  SILAGE  CROP 


417 


base.  The  lower  limit  of  the  curve  is  zero  and  its  upper  limit  is  the 
value  of  A.  Theoretically  these  limits  are  never  reached,  but  practically 
they  are  very  closely  approximated  within  a  short  range  of  t;  the  larger 
the  value  of  K,  the  shorter  the  range  of  t.a 


TARLE  2. — GROWTH  OF  THE  SUNFLOWER  AND  CORN  CROPS:    VALUES  OF  THE  CONSTANTS 
TO  THE  GROWTH  EQUATIONS  OF  FIGS.  5-24 

Data  for  corn  are  from  Bulletin   175,  Purdue  University  Agricultural  Experiment 
Station 


Constituent 

Fig. 

A 

K 

ti 

SUNFLOWER 
Crude  fiber  in  stalk  

5 

2700 

.033 

78.5 

Crude  fiber  in  stalk,  1st  cycle  
Crude  fiber  in  stalk,  2d  cycle  

6 
6 

2200 
480 

.042 
.082 

72.5 
110 

Aluminum  in  stalk  

8 

7.5 

.033 

97 

Iron  in  seed  

17 

.235 

.081 

92 

Calcium  in  seed  

18 

3.3 

.050 

97.5 

Potassium  in  seed  

19 

12.5 

.060 

98 

Phosphorus  in  seed  

20 

2  34 

.054 

100 

Ash  in  seed  

16 

50 

.053 

100 

Dry  matter  in  seed  

9 

1450 

.058 

102 

Crude  fiber  in  seed  

13 

580 

.060 

103.5 

Magnesium  in  seed  

21 

4.3 

062 

104.5 

Sodium  in  seed  

22 

.55 

.045 

106 

Protein  in  seed  

11 

240 

.054 

107 

Sulfur  in  seed  

23 

5.2 

.034 

108 

Aluminum  in  seed  

24 

4 

.060 

108 

Fat  in  seed  

15 

560 

046 

108 

CORN 
Crude  fiber  in  stalk,  1st  cycle  

7 

1030 

075 

66  5 

Crude  fiber  in  stalk,  2d  cycle  .  .  . 

7 

680 

033 

133 

Crude  fiber  in  ear  

14 

350 

.047 

95 

Protein  in  ear  

12 

552 

038 

109 

Dry  matter  in  ear  ....    :  

10 

6000 

.038 

112 

The  above  equation  has  been  applied  to  the  data  of  Table  1,  Rob- 
ertson's method  and  tables  being  utilized  in  the  first  approximation  to 
the  values  of  the  constants.  The  purpose  of  the  present  work  and 
character  of  the  data  hardly  seem  to  necessitate  the  further  refinement 
of  the  estimates  of  the  values  of  the  constants  by  the  method  of  least 
squares,  as  contemplated  by  Robertson's  method.  The  constants  of 
the  equations  as  applied  to  the  data  of  Table  1  and  also  to  similar  data 
by  Jones  and  Huston23  for  the  corn  crop  are  given  in  Table  2.  The 
data  are  shown  graphically  also  in  Figs.  5  to  24  inclusive.  Time  (t) 
is  conveniently  reckoned  in  days  from  the  date  of  planting.  Some  days 
elapsed,  of  course,  before  the  plants  reached  the  height  at  which  they 
were  cut  and  subject  to  measurement.  The  zero  point  of  t  makes  no 

"See  pages  424-28  for  further  discussion  of  this  equation. 


418  BULLETIN  No.  268  [/««', 

difference,  however,  since  the  point  of  origin  of  the  curve  is  virtually 
at  1=^.  x  is  expressed  as  a  percentage  of  A  in  the  graphs. 

Growth  in  Stalk  of  Sunflower  and  Corn 

Crude  Fiber  in  Stalk. — Fig.  5  shows  the  observations  on  the  crude 
fiber  in  the  stalk  of  the  sunflower  and  the  equation  and  the  curve  de- 
scribing them  as  a  single  growth  cycle.  The  curve  gives  a  fair  fit  to 
the  observations.  The  observations,  however,  suggest  a  small  and  rapid 
second  growth  cycle  imposed  upon  the  larger  and  slower  first  growth 
cycle.  In  Fig.  6  the  data  are  treated  from  this  viewpoint  and  a  some- 
what better  fit  of  the  curve  expressing  the  sum  of  the  two  growth  cycles 
is  obtained.  The  root  mean-square  error  of  the  single  cycle  curve  is 
66  pounds,  and  of  the  double  cycle  curve,  40  pounds.  The  difference 
thus  indicated  is  due  primarily  to  the  one  observation  at  t=106;  and 
if  this  observation  is  ignored,  the  errors  are  respectively  45  and  43 
pounds.  The  observations  might  not  warrant  the  assumption  of  a 
second  growth  cycle  except  that  there  are  physiological  grounds  to  ex- 
pect such  a  condition. 

The  development  of  the  seed  head  of  the  plant  may  be  responsible 
for  a  second  growth  cycle  in  the  present  case,  since  there  is  a  consid- 
erable amount  of  fibrous  material  in  the  head.  (The  seeds  only  were 
separated,  the  remainder  of  the  head  being  included  with  the  stalk 
portion  of  the  sample.)  The  plant  ceases  to  grow  in  height  at  about 
the  time  of  pollination  of  the  flowers  (Reed  and  Holland*).  Cessation 
of  growth  in  height  does  not  necessarily  imply  cessation  of  growth  in 
diameter  of  stalk  or  amount  of  leaf  and  stem  material.  In  view  of  the 
lack  of  sufficient  data  as  to  the  crude  fiber  content  of  the  head  (minus 
the  seed)  it  cannot  be  said,  therefore,  that  growth  in  the  head  is  entirely 
responsible  for  the  second  growth  cycle. 

Fig.  7  presents  similar  data  for  the  corn  plant  taken  from  Jones 
and  Huston.23  In  this  case  the  plants  were  cut  at  the  ground  level,  in 
sampling.  The  crop  was  insured  a  regular  minimum  supply  of  water, 
by  irrigation  weekly  if  necessary. 

These  data  may"  be  very  closely  represented  by  a  two-cycle  equa- 
tion, assuming  that  the  second  cycle  is  at  its  maximum  velocity  at  the 
last  observation,  133  days  after  planting.  It  seems  improbable  that 
any  material  growth  occurs  after  this  time  (October  8),  but  this  would 
not  preclude  the  termination  of  a  second  growth  cycle  before  completion 

'Reed  and  Holland40  studying  the  growth  of  the  sunflower  in  height  in  centimeters 
find  the  equation 

log =  0.042   (t  — 34.2) 

254.5 -x 

to  apply.  Time  (t)  is  reckoned  in  days  beginning  some  time  after  planting,  not  defi- 
nitely stated,  so  that  ti  cannot  be  connected  with  the  corresponding  constant  in  the 
crude-fiber  equation  above.  It  may  be  noted  that  their  K  has  the  same  value  as  in 
the  present  crude-fiber  equation  for  the  first  growth  cycle  of  the  stalk. 


1925~\  THE  SUNFLOWER  AS  A  SILAGE  CROP  419 

of  its  full  capacity,  as  by  frosts  or  by  death  of  the  plant  from  other 
cause. 

The  data  on  the  stalk  include  the  husk,  and  the  development  of 
this  organ  may  be  responsible  in  whole  or  in  part  for  the  second  crude- 
fiber  growth  cycle.  According  to  the  equations  for  the  two  cycles,  the 
second  cycle  accounts  for  24.8  percent  of  the  crude  fiber  of  the  stalk 
(that  is,  all  of  the  plant  above  ground  except  the  cob  and  kernels)  133 
days  after  planting.  Schweitzer45  gives  data  which  indicate  19  percent 
of  the  crude  fiber  of  the  stalk  as  present  in  the  husk  131  days  after 
planting.  Grindley*  found  18  percent  of  the  crude  fiber  of  a  100  bushel 
crop  of  corn  to  be  present  in  the  husk.  Accordingly,  the  development 
of  the  husk  may  be  largely  responsible  for  the  second  cycle. 

Assuming  the  data  of  Figs.  6  and  7  to  represent  the  facts  for  the 
sunflower  and  corn  crops,  respectively,  there  is  evident  a  pronounced 
and  significant  difference  in  the  two  crops.  In  the  first,  or  vegetative 
cycle,  the  sunflower  is  slow-growing  (low  value  of  K),  while  the  corn 
is  quick-growing  (high  value  of  K).  In  the  second  cycle,  associated 
with  the  reproductive  activities  of  the  plant,  these  relations  are  reversed, 
i.e.,  the  sunflower  has  a  short  growth  period  and  corn  a  long  period. 
Also,  if  the  indicated  incomplete  development  of  the  second  cycle  for 
the  corn  stalk  correctly  represents  the  facts,  the  two  crops  are  distinctly 
different  in  this  respect.  There  is  indicated,  in  short,  a  very  marked 
difference  in  the  two  crops  with  respect  to  the  relative  development  of 
their  vegetative  and  reproductive  functions.  Further  discussion  of  the 
significance  of  the  differences  in  the  constants  of  the  equations  from  the 
standpoint  of  the  genetic  possibilities  of  the  two  plants  and  the  bearing 
upon  stock-farming  practice  is  given  below  (page  427). 

Aluminum  in  Stalk. — As  mentioned  above,  aluminum  is  the  only 
stalk  constituent  given  in  Table  1  which  does  not  show  a  depletion  in 
absolute  amount  coincident  with  the  development  of  the  seed.  Some 
chemical  difficulties  were  encountered  in  the  aluminum  determinations 
and  this  perhaps  accounts  for  the  irregularity  in  the  observations 
(Fig.  8).  One  observation  (10.86=144.8%  of  7.5  at  t=127)  is 
omitted  in  the  graph  and  disregarded  in  fitting  the  curve. 

The  fact  that  crude  fiber  and  aluminum  alone  do  not  undergo  de- 
pletion suggests  that  they  are  in  some  way  associated.  It  would  be 
possible,  as  in  the  case  of  crude  fiber,  to  treat  the  aluminum  data  as 
representing  a  two-cycle  phenomenon,  but  the  observations  are  so  irreg- 
ular that  the  simple  curve  only  is  used.  Treated  as  representing  a  single 
cycle,  they  may  be  compared  with  the  crude-fiber  curve  of  Fig.  5.  The 
two  equations  have  the  same  value  of  K,  but  quite  different  values  of 
tt.  Aluminum  in  the  stalk  is  directly  proportional  to  the  crude  fiber  of 
18.5  days  preceding.  Assuming  that  it  is  associated  with  the  crude 
fiber,  the  lag  in  its  appearance  supports  the  idea  that  it  is  not  a  neces- 

MJnpublished  data,  Illinois  Experiment  Station. 


420 


BULLETIN  No.  268 


[June, 


. 

(X) 


(XJ 


1925~\  THE  SUNFLOWER  AS  A  SILAGE  CROP  421 

sary  constituent,  but  rather  an  unessential  accumulation  collecting 
mechanically  according  to  the  volume  of  tissues  represented  by  the  mass 
of  the  crude  fiber." 

Growth  in  Seed  of  Sunflower  and  Ear  of  Corn 

Growth  of  the  seed  differs  from  growth  of  the  stalk  in  that  all  of 
its  constituents  as  given  in  Table  1  (except  nitrogen-free  extract)  con- 
tinue to  increase  thruout  the  growth  period. 

Dry  Matter  in  Seed  and  Ear. — Data  for  dry  matter  in  the  seed 
of  the  sunflower  are  given  in  Fig.  9,  and  for  comparison  Jones  and 
Huston's  data  for  the  dry  matter  in  the  ear  of  the  corn  crop  are  given 
in  Fig.  10.  The  value  of  K  for  the  sunflower  is  much  greater  than  for 
the  corn,  that  is,  the  sunflower  has  a  much  shorter  period  of  growth. 
It  is  necessary  in  interpreting  the  corn  data,  on  the  basis  of  the  equation 
used,  to  assume  that  the  ear  is  potentially  capable  of  a  considerably 
greater'  growth  of  dry  matter  than  is  actually  realized. 

Protein  in  Seed  and  Ear. — The  data  for  protein  are  presented  in 
Figs.  11  and  12.  Comparison  of  the  equations  and  curves  leads  to  en- 
tirely similar  deductions  as  to  the  differences  in  the  two  crops,  as  in 
the  case  of  dry  matter. 

Crude  Fiber  in  Seed  and  Ear. — The  data  for  crude  fiber  are  given 
in  Figs.  13  and  14.  The  differences  in  the  equations  and  curves  in  this 
case,  while  of  the  same  kind,  are  not  so  marked  as  noted  for  dry  matter 
and  protein.  It  may  be  noted  also  that  whereas  in  the  case  of  dry 
matter  and  protein  the  values  of  A  are  considerably  greater  for  corn 
than  for  the  sunflower,  this  order  is  reversed  in  the  case  of  crude  fiber. 
Crude  fiber  is  not,  however,  a  desirable  stock  feed  and  85  percent  of  it 
in  an  ear  of  corn  may  be  eliminated  by  the  simple  and  common  pro- 
cedure of  shelling  the  corn.  It  is  not  commercially  practical  to  elimi- 
nate the  crude  fiber  of  the  sunflower  seed  for  stock  feeding. 

Fat  in  Seed. — Fat  or  oil  is  the  principal  product  stored  as  reserve 
nutritive  material  in  the  sunflower  seed.  The  growth  of  the  seed  in 
fat  is  shown  in  Fig.  15.  In  order  to  reconcile  the  observations  and  the 
growth  equation  used  it  is  necessary  to  assume  that  ta  is  considerably 
delayed  for  fat  as  compared  with  the  other  constituents  of  the  seed, 
and  that  the  growth  process  is  terminated  before  its  normal  comple- 
tion. In  this  respect  there  is  similarity  to  the  growth  of  the  ear  of  the 
corn  crop  in  various  constituents  as  above  noted.  This  peculiarity  may 
have  some  significance  in  connection  with  the  possible  improvement 

*The  possible  association  of  aluminum  with  crude  fiber  might  be  investigated  in 
the  seed  of  the  sunflower.  The  seed  contains  some  aluminum  and  a  large  proportion 
of  crude  fiber,  nearly  all  of  which  is  in  the  shell  of  the  seed.  The  shell  can  be  readily 
separated  mechanically  and  determination  of  the  accompanying  separation  of  aluminum 
might  give  some  light  on  the  association  of  the  two.  The  ratio  of  aluminum  to  crude 
fiber  is  much  less  in  the  seed  than  in  the  stalk. 


422 


BULLETIN  No.  268 


[June, 


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THE  SUNFLOWER  AS  A  SILAGE  CROP 


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BULLETIN  No.  268 


[June, 


7925] 


THE  SUNFLOWER  AS  A  SILAGE  CROP 


§ 
(X)  LJJ.MOJJ 


426  BULLETIN  No.  268  [/"«<", 

of  the  sunflower  as  an  agricultural  crop.  The  growth  in  fat  is  undoubt- 
edly associated  with  the  depletion  of  nitrogen-free  extract  noted  in 
Table  1. 

Ash  and  Mineral  Elements  in  Seed. — Data  for  the  ash  are  given  in 
Fig.  16,  and  data  for  the  elements  of  the  ash  are  given  in  Figs.  17  to  24. 
The  figures  for  the  elements  are  given  in  order  of  increasing  value  of  t15 
as  in  Table  2.  The  growth  in  iron  (Fig.  17)  seems  distinctly  different, 
in  that  it  is  accumulated  apparently  at  a  very  early  stage  of  growth  of 
the  seed.  It  may  be  noted  that  phosphorus  (Fig.  20)  has  the  same 
value  of  K  as  protein  (Fig.  11).  Protein  is  thus  proportional  to  the 
phosphorus  of  seven  days  preceding.  The  observations  on  aluminum 
(Fig.  24)  are  very  irregular.  The  value  of  K  has  been  arbitrarily  taken 
to  be  the  same  as  that  for  crude  fiber. 

Significance  of  the  Growth  Constants 

The  comparisons  made  here  between  the  sunflower  and  corn  crops 
are  faulty  in  that  the  crops  were  not  grown  under  the  same  conditions. 
The  corn  in  the  Indiana  experiments  yielded  76  bushels  per  acre, 
which  is  considerably  more  than  the  yield  that  might  be  expected  under 
the  sunflower  crop  conditions. 

Environmental  conditions  affect  the  values  of  the  constants,  espe- 
cially A,  in  the  equation  used  to  describe  growth.  The  significance  of 
the  constants  becomes  clearer  by  considering  the  derivation  of  the 
equation. 

Derivation  of  Growth  Equation.* — The  equation  is  that  expressing 
the  course  of  a  monomolecular  chemical  reaction  which  is  autocatalyzed. 
The  velocity  of  such  reaction  at  any  moment  is  proportional  to  the 
product  of  the  amount  of  untransformed  and  transformed  material. 
It  is  expressed  as: 

V-Ma-x)  (2) 


dt 

where  a  is  the  amount  of  reacting  material  to  start  with;  x  is  the  amount 
converted  at  any  later  time,  t;  and  kj  is  a  constant.  It  is  apparent  that 
the  greatest  velocity  will  be  at  the  time  when  x=a— x=1/4  a.  This  is 
accordingly  the  point  of  inflection  in  equation  (1).  Equation  (2)  inte- 
grated gives: 

log =  K(t-tl)  (3) 

a  —  x 

in  which  K=k1a  and  tt  is  the  time  when  x=%  a. 


'Adapted;  see  Robertson43  for  fuller  treatment. 


1925~\  THE  SUNFLOWER  AS  A  SILAGE  CROP  427 

This  pertains  to  the  forward  reaction.  Where  the  reverse  reaction 
proceeds  sufficiently  so  that  it  needs  to  be  taken  into  account  we  have: 

-^  =  k1(a-x)-k2x2  (4) 

dt 

k2  being  the  velocity  constant  of  the  reverse  reaction,  and  other  notation 
as  above.   Equation  (4)  rearranged  and  integrated  gives: 

log— =K(t-tl)  (1) 

A~x  i, 

KJ  a 

that  is,  the  equation  used,  and  in  which  A  =  — — ,  other  notation 

as  above. 

In  applying  equation  (1)  to  the  expression  or  interpretation  of 
growth  phenomena  it  is  obviously  inadequate  to  include  the  entire  meta- 
bolism of  the  organism  involved  in  growth.  It  is  conceivable,  however, 
that  it  may  represent  some  one  reaction  upon  which  the  other  growth 
activities  depend,  and  being  the  limiting  factor  in  the  velocity  of  growth 
serves  to  determine,  as  well  as  to  describe,  the  whole  growth  process. 

Genetic  Significance  of  the  Difference  in  the  Constants. — In  equa- 
tions (2)  and  (4)  ^  and  k2  are  constants,  unaffected  by  the  value  of  a 
and  specific  for  the  particular  chemical  reaction  concerned.  In  the  liv- 
ing organism,  a  is  presumably  subject  to  some  modification  according 
to  the  level  of  nutrition.  Accordingly  A  in  equation  (1)  may  vary 
considerably  owing  to  the  nutritional  environment,  but  K/A(=k1-|-k2)a 
should  be  theoretically  unaffected  by  the  nutritional  level  and  should 
afford  an  index  of  inherent  growth  qualities  of  the  organism. 

The  farmers'  practical  interest,  however,  in  the  sunflower  and  com- 
peting crops  is  in  the  yield  per  acre,  that  is,  A  itself  in  the  equations 
as  above  applied.  But  in  K/A,  a  large  value  of  A  tends  to  give  a  small 
value  of  K/A.  A  large  value  of  K  gives  a  large  value  of  K/A,  but  a 
large  value  of  K  means  a  short  growing  period,  which  is  associated  with 
a  low  yield.  That  is,  K/A  as  a  specific  constant  varies  inversely  with 
the  crop  yield,  as  between  different  species  or  varieties.  If  K/A  is  a 
specific  constant,  independent  of  environment,  then  its  reciprocal,  A/K, 
is  likewise  a  specific  constant  independent  of  environment  and  affords 
an  equally  fundamental  index  of  inherent  growth  limitations.  The  ex- 
pression A/K  has  the  advantage  (for  the  present  purpose)  of  varying 
directly  with  (not  necessarily  in  exact  proportion  to)  the  agricultural 


*In  the  equations  above-  K  =  kia  and  A  = .   Hence 

K/A  — =  k,  +  kz.    See  Robertson,  page  39. 


428  BULLETIN  No.  268  [June, 

value  of  the  crop.  Where  K/A  is  a  specific  growth  velocity  constant, 
A/K  is  a  specific  growth  capacity  constant.  Comparison  on  this  basis 
theoretically  eliminates  the  effect  of  environmental  differences.  The 
constants  A/K  for  the  sunflower  and  corn  crops  as  derived  from  the 
foregoing  growth  equations  are  given  in  Table  3. 

From  Table  3  it  appears  that  the  sunflower  is  preeminently  a  stalk 
crop  and  a  crude-fiber  crop,  while  the  corn  is  preeminently  a  grain  crop. 
When  the  crude  fiber  in  the  stalk  of  the  sunflower  is  compared  with 
that  in  the  corn,  the  sunflower  is  found  to  have  a  much  higher 
value  than  the  corn  (440:165=2.7:1).  When  the  dry  matter  in 
seed  and  ear  are  compared,  the  sunflower  has  a  much  lower  value  than 
the  corn  (250:1579=1:6.3).  Again,  as  to  the  ratio  of  crude  fiber 

TABLE     3. — COMPARISON    OF     SPECIFIC    GROWTH-CAPACITY    CONSTANTS     OF     CERTAIN 
CONSTITUENTS  OF  THE  SUNFLOWER  AND  CORN  CROPS 


A/K 

x  102 

Sunflower 

Corn 

Crude  fiber  in  stalka  

440 

165 

Crude  fiber  in  seed  or  ear  

97 

74 

Dry  matter  in  seed  or  ear  

250 

1579 

Protein  in  seed  or  ear  

44 

145 

"Weighted  average  of  first  and  second  cycles. 

in    stalk    to    dry    matter    in    seed    or    ear,    the    sunflower    is    much 
higher  ( ~^:  '•  =  17:1  1.     This  is  striking  evidence  of  the  inherent 

superiority  of  the  corn  crop  as  a  stock  crop.  Possibly  the  sun- 
flower is  better  fitted  to  survive,  if  it  were  only  a  matter 
of  natural  struggle  for  existence,  but  as  a  cultivated  crop  the 
corn  is  evidently  much  more  highly  improved.*  Undoubtedly  the 
sunflower  may  be  much  improved  by  breeding  and  selection,  but 
starting  with  its  apparent  inherent  handicap  of  running  to  stalk  and 
crude  fiber,  it  would  seem  to  have  little  prospect  of  ever  competing  with 
corn  even  as  a  silage  crop,  where  conditions  permit  the  growing  of  corn. 
As  a  seed  crop,  the  sunflower  has  the  further  unfavorable  features  of  a 
very  limited  time  when  it  may  be  harvested  without  excessive  loss  of 
seeds  by  shattering  and  the  difficulty  of  harvesting  and  storing  the  seed. 
As  indicated  by  the  data  of  Tables  2  and  3,  the  sunflower,  as  com- 
pared with  corn,  produces  both  absolutely  and  proportionately  to  the 
other  constituents  a  very  large  amount  of  crude  fiber.  The  crude  fiber 
of  farm  crops  tends  to  decrease  somewhat  in  digestibility  as  the  crop 
grows  mature,  reducing  the  palatibility  of  the  crop  as  a  feed.  Herein, 

"Possibly  the  growth-equation  constants  as  used  are  not  entitled  to  the  significance 
implied  in  the  present  treatment.  The  proof  of  their  value  is  to  be  found  in  a  wider 
application  of  the  method  under  various  conditions  and  a  critical  scrutiny  of  the  results 
as  to  their  rationality  and  usefulness. 


1925}  THE  SUNFLOWER  AS  A  SILAGE  CROP  429 

apparently,  lies  the  reason  why  the  sunflower  should  be  harvested,  for 
silage,  at  an  early  stage  of  maturity  if  the  best  use  is  to  be  made  of  the 
crude  fiber  of  the  crop.  Corn  harvested  at  an  early  stage  of  maturity 
may  develop  an  objectionable  degree  of  acidity  in  the  silage,  but  the 
sunflower  does  not  seem  to  be  subject  to  this  disadvantage  of  early 
harvest. 

COMPOSITION  OF  CROP 

The  percentage  composition  of  the  fresh  green  crop  is  given  in 
Table  4,  and  the  percentage  composition  of  the  dry  matter  of  the  crop 
is  given  in  Table  5. 

The  most  striking  change  is  in  the  water  content  which,  starting  at 
89  percent  65  days  after  planting,  falls  off  gradually  at  first  and  then 
very  rapidly  after  117  days.  Up  to  117  days,  there  is  an  excessive 
amount  of  water  in  the  crop  for  silage  purposes.  Placed  in  the  silo  in 
this  condition,  there  is  a  loss  of  plant  juices  by  seepage  from  the  silo. 
It  is  therefore  advisable  to  allow  the  plants  to  dry  to  some  extent  in  the 
field  after  cutting  them  and  before  hauling  them  to  the  silo.  After  117 
days  the  water  content  falls  off  so  rapidly  that  ten  days  later  it  is  too 
low  for  best  preservation  in  the  silo. 

The  changes  in  percentage  water  content  of  course  affect  the  per- 
centage content  of  the  other  constituents.  Changes  in  these  are  best 
considered,  therefore,  on  the  basis  of  the  composition  of  the  dry  matter 
as  given  in  Table  5.  It  may  be  noted  that  the  proportion  of  fat  in- 
creases markedly  in  the  seed  as  growth  proceeds.  The  proportion  of 
crude  fiber  also  increases  markedly  in  both  stalk  and  seed.  The  other 
constituents — ash  and  nitrogen-free  extract,  particularly  the  latter — 
decrease  with  maturity.  The  crude  protein  of  the  stalk  likewise  de- 
creases with  advancing  maturity. 

YIELD  AND  COMPOSITION  OF  CROP  AS  ENSILED 

Samples  of  the  main  crop  as  it  was  being  ensiled  at  three  different 
stages  of  maturity  were  obtained  by  taking  small  random  samples  from 
the  silo  during  the  filling  process.  These  samples  were  collected  in  cov- 
ered milk  cans.  At  the  close  of  the  day's  run,  this  large  composite 
sample,  having  a  bulk  of  fifteen  to  twenty-five  gallons,  was  subsampled 
and  the  subsamples  dried  as  usual.  The  analyses  of  these  samples, 
together  with  calculations  of  yield  of  the  crop  per  acre,  shown  as  Tables 
6  and  7,  serve  as  a  check  upon  the  field  samples  taken  about  the 
same  dates  and  from  which  the  composition  of  the  crop  was  determined, 
as  presented  in  Tables  4  and  5. 

Thus  sample  No.  5  corresponds  closely  to  the  calculated  results 
from  the  combination  of  samples  3  and  4;  sample  No.  11  to  samples  8 
and  9;  sample  No.  25  to  samples  26  and  27.  It  will  be  noted  that  the 
results  obtained  by  the  two  methods  of  sampling  are  in  general  agree- 
ment. The  yield  of  fresh  matter  in  the  crop  is  lower  in  two  of  the  cases 


430 


BULLETIN  No.  268 


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BULLETIN  No.  268 


[June, 


where  the  yields  were  calculated  from  the  weights  of  the  loads  delivered 
to  the  silo  and  from  the  samples  thereof,  than  the  yields  calculated 
from  the  field  samples  taken  at  corresponding  dates  and  shown  in 
Table  1.  As  the  field  was  fully  a  mile  from  the  silos,  it  is  believed  that 
these  differences  are  due,  in  part,  to  loss  of  moisture  from  the  plants 
during  the  brief  time  they  were  exposed  to  a  drying  atmosphere  after 
they  were  cut  and  before  they  were  weighed.  Another  contributing 
factor  was  that  the  plants  as  harvested  for  the  silo  were  cut  at  a  greater 
height  from  the  ground  than  when  obtaining  the  field  samples. 

COMPARATIVE  YIELDS  OF  SUNFLOWERS  AND  CORN 

A  ten-acre  portion  of  the  field  upon  which  the  sunflowers  were 
grown  was  planted  to  field  corn.  The  manner  of  planting  was  that  usu- 
ally followed  in  growing  the  crop  for  grain,  that  is,  planting  in  rows  3 
feet  6  inches  apart  and  in  hills  3  feet  6  inches  apart  in  the  row.  The 
crop  yielded  somewhat  less  forage  per  acre  than  corn  grown  for  silage 

TABLE  8. — COMPARATIVE  YIELDS  OF  SUNFLOWERS  AND  CORN* 
Pounds  per  acre 


Substance 

Sunflower 

Con 

i  crop 

crop 

Field  A 

Field  B 

Fresh  matter  

34  945 

19  567 

14  340 

Dry  matter  

8  248 

5  935 

4  808 

Crude  ash  

901 

352 

288 

Crude  protein  

612 

531 

414 

Crude  fiber  

3  119 

1  275 

985 

N-free  extract  

3  184 

3  638 

2  991 

Carbohydrates  

6  303 

4  913 

3  976 

Crude  fat  

432 

139 

130 

aData  for  sunflowers  taken  from  Table  1;  samples  harvested  September  12.  Data  for 
corn  are  from  a  crop  grown  for  silage  in  the  same  season,  yielding  39  bushels  of  shelled 
corn  on  Field  A  and  31  bushels  on  Field  B.  Corn  crop  harvested  August  25  to  31. 

(drilled)  for  the  same  season,  only  5.93  tons  per  acre  of  fresh  matter 
containing  4,113  pounds  of  dry  matter.  These  data  are  not  considered 
representative  of  corn  grown  for  silage.  Data  for  two  other  fields  of 
corn,  grown  the  same  season  for  silage  purposes,  are  considered  more 
representative  of  the  nutrient  yield  of  silage  corn,  and  are  therefore 
brought  together  in  Table  8  for  comparison  with  the  data  of  the  sun- 
flower crop. 

The  sunflower  crop,  at  the  time  the  yield  of  dry  matter  had  reached 
its  maximum,  contained  50  percent  more  dry  matter  than  the  corn. 
The  sunflower  crop  at  that  stage  had  declined  greatly  in  water  content, 
but  even  then  the  ratio  of  dry  substance  to  water  was  about  1:3.2, 
whereas  in  corn  it  was  1 :2.2. 


1925] 


THE  SUNFLOWER  AS  A  SILAGE  CROP 


435 


The  differences  in  the  character  of  the  nutrients  in  the  two  crops 
are  well  illustrated  in  this  table.  The  yields  of  crude  fiber  and  nitrogen- 
free  extract  of  sunflowers  are  about  equal  in  amount,  but  in  corn  the 
ratio  of  the  two  classes  of  nutrients  is  approximately  1:3.  The  yield 
of  crude  fat  in  the  sunflowers  is  much  greater  proportionately  than  that 
in  the  corn  crop. 

Losses  in  Leaves. — Evidence  of  the  loss  of  dry  matter  from  the 
sunflower  crop  was  sought  by  a  study  of  the  composition  of  living  and 
dead  leaves  of  the  same  plant.  Eighty-four  fresh  green  leaves  and  an 

TABLE  9. — COMPOSITION  OF  THE  DRY  MATTER  OF  FRESH  GREEN 

AND  DEAD  SUNFLOWER  LEAVES 
Expressed  in  percentage  of  the  dry  matter 


Ash 

Crude 
protein 

Crude 
fiber 

N-free 
extract 

Crude 
fat 

Fresh  green  leaves  

18.06 

17.25 

12.28 

47.06 

5.36 

Dead  leaves  

17.94 

15.59 

17.38 

44.04 

5.06 

TABLE  10. — AMOUNTS  OF  VARIOUS  CONSTITUENTS  PER  100  SUNFLOWER  LEAVES 
Expressed  in  grams 


Dry 

matter 

Ash 

Crude 
protein 

Crude 
fiber 

N-free 
extract 

Crude 
fat 

Fresh  green  leaves  .  .  . 
Dead  leaves  

306.4 
191.5 

55.3 
34.3 

52.8 
29.9 

37.6 
33.3 

144.2 
84.3 

16.4 
9.7 

equal  number  of  apparently  dead,  dried  leaves  were  collected,  the  same 
number  of  each  kind  being  selected  from  each  plant.  Care  was  taken 
to  choose  leaves  corresponding  approximately  in  surface  area.  The 
leaves  were  weighed,  dried  under  the  same  conditions  as  the  field 
samples,  and  submitted  for  analysis.  The  results  of  these  analyses  and 
calculations  relative  thereto  are  shown  in  Tables  9  and  10. 

The  dead  leaves  contained  62.5  percent  as  much  dry  matter  as 
those  which  were  living  at  the  time  of  collection.  The  dead  leaves  were 
relatively  poorer  in  crude  protein  and  nitrogen-free  extract,  but  higher 
in  crude  fiber  than  the  others. 

These  data  do  not,  however,  necessarily  prove  that  sunflower 
leaves,  following  cessation  of  growth,  lose  their  nutrients  thru  weather- 
ing, since  it  is  possible  that  some  of  these  constituents  are  withdrawn 
to  other  parts  of  the  plant.  The  severe  attacks  of  sunflower  rust  may 
have  rendered  the  infected  leaves  subject  to  losses  by  weathering. 

YIELD  OF  CROP  IN  TERMS  OF  DIGESTIBLE  NUTRIENTS 

One  of  the  most  important  criteria  of  the  value  of  a  crop  for  silage 
purposes  is  the  yield  of  the  crop  in  terms  of  digestible  matter.  The  data 
obtained  in  this  study  include  the  yields  per  acre  of  total  crude  nutri- 


436  BULLETIN  No.  268  [June, 

ents.  Portions  of  the  main  crop  were  ensiled  at  three  different  stages 
of  development  and  studies  were  made  of  the  feeding  value  of  the  silage 
produced  (see  Bulletin  253  of  this  Station).  The  coefficients  of  digesti- 


FIG.  25. — CUTTING  SUNFLOWERS  IN  THE  FIELD 

Showing  condition  of  the  crop  at  the  first  stage  of  maturity,  as  harvested  for  silage 
87  days  after  planting.  The  crop  was  cut  by  hand  so  as  to  secure  a  more  accurate 
determination  of  the  crop  yield.  The  yield  per  acre  was  17  tons  (85  percent  water). 

bility  of  the  silage  which  were  obtained  in  those  studies  were  applied 
to  the  data  obtained  in  the  field  studies  and  thus  the  yields  of  digestible 
nutrients  per  acre  were  calculatetd.  The  results  are  presented  graph- 
ically in  Fig.  26. 

Marked  increases  in  yields  of  digestible  crude  fiber  and  digestible 
crude  fat  were  obtained  in  the  later  harvests,  while  there  was  a  slight 
falling  off  of  the  digestible  crude  protein  and  a  marked  decline  of  the 
nitrogen-free  extract.  By  postponing  harvest  as  long  as  practicable 
there  was  a  gain  of  about  9  percent  in  yield  of  total  digestible  nutrients 
per  acre. 

It  is  believed,  however,  that  the  method  of  determining  the  amount 
of  digestible  matter  in  the  crop  at  the  time  of  the  third  harvest,  namely, 
the  application  of  the  coefficients  of  digestion  secured  from  the  silage 
produced  from  the  second  harvest,  very  considerably  overestimates  the 
actual  yield  of  digestible  nutrients  at  that  stage.  The  results  were  cal- 
culated in  this  manner  in  order  to  give  a  comparison  of  the  yields  of 
digestible  substance  at  these  different  stages.  It  is  likely  that  the  actual 
yield  of  digestible  matter  at  the  time  of  the  third  harvest  was  less  than 
at  the  second.  For  a  further  discussion  of  this  subject,  see  Bulletin  253. 

FERTILITY  RELATIONSHIPS 

The  extensive  use  of  sunflowers  as  a  silage  or  seed  crop  would 
make  it  very  desirable  to  have  information  regarding  the  fertility  rela- 
tionships and  soil  requirements  of  the  crop.  The  comparatively  small 
amount  of  information  at  hand  regarding  these  phases  of  sunflower  cul- 


1925'\ 


THE  SUNFLOWER  AS  A  SILAGE  CROP 


437 


ture  made  it  seem  advisable  to  obtain  detailed  information  regarding 
the  amounts  of  the  various  ash  elements  in  the  crop. 


Q-IZ-21 
9-  I  -'21 
9-22-ZI 


Crude        Crude      N-Free    Ether  £xtr.  Total 
Prote/n       F/ber     Extract       x8%      D/'g  Nut. 

FIG   26. — YIELDS   OF    DIGESTIBLE    MATTER    IN    SUNFLOWERS 
HARVESTED  FOR  SILAGE  AT  THREE  DIFFERENT 

STAGES  OF  GROWTH 

Calculations   are  based  on   digestibility  of  the  silage  as 
determined  with  dairy  cows. 

Fertilizing  Elements  Removed. — The  amount  of  the  fertilizing  ele- 
ments removed  from  one  acre  in  the  sunflower  crop  is  shown  in  Table  1. 
It  is  very  evident  that  there  is  a  rapid  increase  in  the  crop  of  some 
of  the  elements,  notably  potassium,  calcium,  and  nitrogen  during  the 
first  part  of  the  period  of  observation,  and  almost  as  rapid  a  decline  in 
the  latter  part  of  the  period.  Magnesium  and  sulfur  show  trends  in 
the  same  general  direction. 


438  BULLETIN  No.  268  {]unt, 

The  sunflower  crop  removed  a  very  large  amount  of  ash  per  acre, 
a  total  of  900  pounds  as  a  maximum.  The  element  potassium  com- 
prized about  141  pounds  of  this,  while  calcium  followed  with  119 
pounds,  magnesium  with  54  pounds,  sulfur  with  30  pounds  and  phos- 
phorus with  10  pounds.  The  amount  of  nitrogen  in  the  crop  was  about 
98  pounds  per  acre.  In  terms  of  fertilizers  of  the  best  grade,  these 
amounts  are  approximately  equivalent  to:  potassium  sulfate,  335  pounds 
or  kainit,  1,420  pounds;  sodium  nitrate,  600  pounds;  limestone,  300 
pounds;  rock  phosphate,  110  pounds. 

Fertilizing  Elements  in  Seed. — The  amount  of  nitrogen  and  ash  re- 
moved from  the  soil  in  the  seed  of  the  sunflower  crop  was  very  much 
less  than  that  in  the  stalks.  Nitrogen  was  present  in  the  seeds  in 
amounts  equal  to  about  one-half  to  two-thirds  that  of  the  total  ash. 
Potassium  far  exceeded  in  quantity  the  other  mineral  elements,  being 
nearly  equal  to  that  of  the  sulfur,  magnesium,  calcium,  and  phosphorus 
combined. 

Ash  Constituents  per  Ton.— The  yield  of  sunflowers  per  acre  is  of 
course  dependent  upon  soil,  climate,  and  other  factors,  and  is  therefore 
subject  to  variation.  Hence,  the  yields  of  ash  constituents  have  been 
expressed  in  terms  of  their  amount  per  ton  of  fresh  matter  and  per  ton 
of  dry  matter,  of  the  stalks,  seed,  and  whole  crop.  These  data,  shown 
in  Tables  11  and  12,  bring  out  the  fact  that  the  ash  formed  a  larger 
part  of  the  dry  matter  of  both  seed  and  stalk  during  the  immature 
stages  than  during  the  more  advanced  stages.  This  change  was  gradual, 
but  quite  marked  with  the  principal  constituents,  potassium  and  calcium. 
Some  of  the  other  elements  show  the  same  tendency,  altho  this  is  not  so 
pronounced,  especially  in  the  seed. 

Composition  of  the  Ash. — It  was  shown  that  there  was  a  pro- 
nounced variation  in  the  proportions  of  the  organic  constituents  during 
development  of  the  crop,  but  this  variation  does  not,  in  general,  hold  to 
so  great  an  extent  for  the  inorganic  constituents  (Table  13).  The  most 
notable  exception  to  this  condition  is  in  the  case  of  aluminum,  the  de- 
terminations of  which  seem  to  indicate  a  gradually  increasing  propor- 
tion of  this  element  during  the  growth  of  the  crop.  The  figures  for  iron 
in  the  early  samples  are  lower  than  in  the  later  ones,  and  the  data  for 
sodium  lack  uniformity,  but  upon  the  whole  the  data  indicate  relatively 
little  change  in  the  proportions  of  the  ash  formed  by  the  other  elements 
during  the  growth  period  studied. 

Potassium  comprized  one-sixth  or  more  of  the  total  ash  of  the  crop 
and  about  one-fourth  of  the  total  ash  of  the  seed.  Calcium  was  the 
second  greatest  ash  element  of  the  crop,  but  the  seed  contained 
only  one-half  as  much  as  the  stalk  portion  of  the  crop.  Magnesium, 
sulfur,  and  phosphorus  followed  in  magnitude  in  the  order  named,  in 
the  total  crop,  but  the  distribution  in  the  seed  of  the  fully  ripe  crop  fol- 
lowed the  order  potassium,  sulfur,  magnesium,  calcium,  phosphorus. 


7P25] 


THE  SUNFLOWER  AS  A  SILAGE  CROP 


439 


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1925] 


THE  SUNFLOWER  AS  A  SILAGE  CROP 


441 


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442 


BULLETIN  No.  268 


[fum, 


A  noteworthy  feature  of  the  sunflower  ash,  not  commonly  found 
in  plants,  is  the  presence  of  aluminum  in  significant  amounts.  Pal- 
ladin35  states  that  "aluminum  occurs  in  plant  ash  rather  infrequently." 
Pfeffer36  agrees  with  the  above  statement,  for  he  says,  "Aluminum,  tho 
universally  distributed,  is  present  only  in  small  amount  in  most  plants, 
except  in  Lycopodium  chamaecyparissus  and  L.  alpinum,  where  it  forms 
22  to  27  percent  of  the  ash."  Jost26  states,  "Thus  it  would  not  be  sur- 
prising ...  if  it  turned  out  that  aluminum,  which  forms  22  to  39 

TABLE  14. — EFFECT  OF  TIME  OF  PLANTING  UPON  YIELDS  OF  THE  SUNFLOWER  CROP 

COMPUTED  FROM  WEIGHTS  OF  RANDOM  SAMPLES  (TAKING  PLANTS  IN  DEFINITE 

SEQUENCE)  AND  ANALYSES  OF  SUBSAMPLES  THEREOF 

Pounds  per  acre 


Sample 
No. 

Date 

planted 

Date 

harvested 

Age  of 
crop 

Distance 
of  plants 
in  row 

Part  of 
crop 

Fresh 
matter 

Water 

Dry 

matter 

28  

1921 
6-8 

1921 
9-24 

days 
108 

inches 
10  02 

Whole... 

20  214 

14  989 

5  225 

29   . 

6-29 

9-24 

87 

17  85 

Whole.. 

13  193 

10  943 

2  250 

35     ... 

6-29 

10-6 

99 

18  54 

Whole.. 

5  888 

4  532 

1  356 

30.. 

7-20 

9-24 

66 

9  53 

Whole.. 

10  189 

8  888 

1  301 

36  

7-20 

10-6 

78 

10  69 

Whole.. 

7  778 

6  509 

1  269 

37  

7-20 

10-24 

96 

13.57 

Whole... 

4  345 

3  117 

1  228 

Yield  of  the  Constituents  of  the  Dry  Matter 


Sample 

No. 

Ash 

Crude 
protein 

Crude 
fiber 

N-free 
extract 

Carbo- 
hydrates 

Fat 

28  

687 

560 

1  971 

1  847 

3  818 

160 

29.. 

384 

336 

661 

808 

1  469 

61 

35  

167 

160 

545 

435 

980 

49 

30.. 

232 

272 

297 

474 

771 

26 

36  

170 

192 

352 

517 

869 

38 

37  

143 

176 

353 

496 

849 

60 

percent  of  the  ash  of  Lycopodium  chamaecyparissus  .  .  .  and  yet  ap- 
pears in  the  minutest  traces  in  most  plants,  including  several  other 
species  of  Lycopodium,  has  a  special  function  to  perform  in  these  plants. 
Large  quantities  of  aluminum  occur  in  species  of  Symplocos  and  Orites 
(Czapek  II).  Jamano  (Bot.  Centrbl.  99,  2)  found  that  aluminum  was 
of  service  in  the  development  of  barley." 

THICKNESS  OF  PLANTING 

It  was  planned  to  secure  data  on  the  comparative  yields  of  sun- 
flowers planted  thickly  and  thinly.  The  main  planting  was  expected  to 
give  a  stand  of  plants  8  inches  apart  in  the  row,  the  thin  planting  16 
inches,  and  the  thick  planting  5  inches,  but  the  results  were  as  shown 


19251 


THE  SUNFLOWER  AS  A  SILAGE  CROP 


443 


in  Table  6,  samples  Nos.  5,  11,  and  25  representing  the  first  or  main 
planting,  No.  10  the  thin  planting,  and  No.  24  the  thick  planting.  The 
differences  in  thickness  of  the  plants  in  the  various  plots  were  too  small 
to  give  conclusive  results. 

TIME  OF  PLANTING 

The  data  shown  in  Tables  4,  5,  and  14  include,  under  samples  Nos. 
28,  29,  35,  30,  36,  and  37,  data  obtained  from  the  plantings  of  sunflow- 
ers made  at  intervals  of  twenty-one  days  following  the  planting  of  the 


(T670J 


5600 


S-IS-^I  Harvested  9-2Z-2/ 
6-Q-2I  •  9-24-2/ 

6-29-21 
7-20-ZI 


Dry         Crude        Crude 
Matter  Prote/n       Fiber 


//-free       Ether 
Extract    Ext.x2%. 


FIG.  27. — YIELDS  OF  CRUDE  NUTRIENTS  IN  THE  SUNFLOWER 
CROP,  AS  AFFECTED  BY  TIME  OF  PLANTING 

main  crop,  from  which  the  bulk  of  the  data  is  derived.  Samples  from 
the  later  plantings  were  taken  in  the  same  manner  as  from  the  earliest 
planting. 

Chief  interest  in  a  study  of  the  best  time  for  planting  sunflowers  is 
centered  about  the  comparative  yields  per  acre  from  sunflowers  planted 


444 


BULLETIN  No.  268 


[June, 


at  different  times.    These  data  are  presented  in  Table  14  and  illustrated 
in  Fig.  27. 

The  differences  in  yield  of  the  various  plantings  is  very  striking. 
This  is  well  brought  out  in  a  comparison  of  the  yields  of  dry  mat- 
ter, but  the  yields  of  the  various  constituents  of  the  dry  matter  show 


FIG.  28. — SUNFLOWERS  GROWN  TO  STUDY  EFFECT  OF  TIME  OF 

PLANTING  UPON  YIELDS 

View  of  first,  second,  and  third  plantings  on  July  19;  planted  May  18,  June  8,  and 
June  29,  respectively. 


FIG.  29. — LATE  CROPS  OF  SUNFLOWERS  GROWN  TO  STUDY  EFFECT  OF 

TIME  OF  PLANTING  UPON  YIELDS 

View  of  second,  third,  and  fourth  plantings  on  August  22;  planted  June  8.  June  29, 
and  July  20,  respectively. 


similar  relationships.  The  dry-matter  yield  of  the  later  plantings  ex- 
pressed in  proportions  of  that  of  the  first  planting,  were  five-eighths, 
one-fourth,  and  one-sixth.  As  is  pointed  out  below,  these  proportions 
do  not  hold  for  the  yield  of  all  the  constituents  of  the  dry  matter.  The 
later  samples  varied  somewhat  in  composition  from  the  crop  of  the  first 


1925}  THE  SUNFLOWER  AS  A  SILAGE  CROP  445 

planting.  The  yield  of  crude  fat  in  the  later  plantings  is  materially  less, 
particularly  in  the  third  and  fourth  plantings,  because  of  the  lack  of 
seed  development.  Practically  no  seeds  developed  in  the  last  crop, 
altho  it  was  sampled  as  late  as  October  24.  In  spite  of  frosts  severe 
enough  to  kill  the  corn  plants  many  of  the  sunflower  plants  were  still 
living  at  that  time. 

Several  factors  seemed  to  contribute  to  the  failure  of  the  later 
plantings  to  produce  yields  equal  to  that  of  the  early  one.  Dry  weather 
interfered  with  the  germination  of  the  third  planting,  made  June  29. 
The  effect  of  this  is  shown  by  the  distance  of  the  plants  in  the  rows 
being  more  than  60  percent  greater  than  that  of  the  first  two  plantings. 
The  later  plantings  appeared  to  be  more  susceptible  to  disease  than  the 
first  planting,  for  it  was  found  in  taking  the  samples  that  many  of  the 
plants  had  become  partially  decayed  and,  being  broken  over,  were  not 
in  position  to  be  harvested  by  the  usual  methods. 

Only  a  few  plants  of  the  third  planting  grew  well-developed  heads, 
and  of  these  only  a  part  matured  seed.  The  plants  of  the  fourth  plant- 
ing had  attained  a  height  of  about  four  and  one-half  feet  on  October  6, 
having  shown  practically  no  development  since  September  24.  Most 
of  these  plants  blossomed,  but  very  few  developed  any  seed. 

The  composition  of  samples  from  the  later  plantings  is  similar  to 
that  of  the  samples  from  the  first  planting  taken  about  the  same  num- 
ber of  days  after  planting,  except  that  the  samples  from  the  later  plant- 
ings were  higher  in  dry-matter  content  and  thus  higher  also  in  most 
of  the  constituents.  When  compared  upon  the  dry-matter  basis,  the 
later  plantings  were  found  to  contain  a  greater  proportion  of  crude  pro- 
tein and  ash,  to  be  very  similar  in  fiber  content  to  the  first  planting,  and 
to  be  lower  in  nitrogen-free  extract. 

It  is  self-evident  that  the  character  of  the  growing  season  of  any 
one  year  plays  an  important  part  in  determining  yields  and  also  the 
composition  of  the  crop.  Seasonal  differences  affecting  the  yield  and 
composition  of  the  sunflower  crops  produced  from  seed  planted  at  dif- 
ferent times  during  the  same  season  were  not  taken  into  account  in  the 
present  investigations. 

SUMMARY  AND  CONCLUSIONS 

Data  on  the  yield  and  composition  of  a  sunflower  crop  grown  in 
1921  were  obtained  from  samples  collected  in  the  field  at  eight  stages 
of  growth  and  from  the  crop  as  ensiled  at  three  stages  of  growth.  These 
data  pertain  to  fresh  matter,  dry  matter,  crude  protein,  crude  fat,  crude 
fiber,  nitrogen-free  extract,  ash,  and  the  elements  Al,  Ca,  Fe,  Mg,  P, 
K,  Na,  and  S;  all  in  stalk  and  seed  separately.  The  feeding  value  of 
the  silage  and  digestibility  factors  were  determined  for  the  three  stages 
(reported  in  Bulletin  253).  Thickness  and  time  of  planting  were  also 
studied.  A  review  of  literature  has  been  included,  and  data  from  Bui- 


446  BULLETIN  No.  268  [/MM-?, 

letin  175  of  the  Indiana  Experiment  Station,  on  the  corn  crop,  have 
been  used  in  making  comparisons. 

Data  from  the  field  samples  have  been  analyzed  mathematically 

X 

(following  Robertson)  by  use  of  the  equation,  log =  K  (t  —  tx), 

A  —  x 

in  which  x  is  the  growth  accomplished  at  any  time,  t,  and  A,  K,  and  tx 
are  constants.  Each  of  the  constituents  of  the  seed  (except  nitrogen- 
free  extract)  exhibits  the  reverse  curve  so  generally  characteristic  of 
growth  in  animals  and  annual  plants.  In  the  stalk,  crude  fiber  and 
aluminum  only  exhibit  the  same  trend,  the  various  other  constituents 
undergoing  marked  depletion  coincident  with  seed  development.  In 
the  stalk  of  both  sunflower  and  corn,  growth  in  crude  fiber  is  interpreted 
as  a  two-cycle  phenomenon.  In  the  first,  or  vegetative,  cycle  the  sun- 
flower is  slow-gr owing  while  corn  is  quick-growing;  in  the  second  or 
reproductive  cycle,  the  reverse  is  true.  The  specific  growth-capacity 
constants  (A/K)  of  the  two  crops  indicate  comparatively  that  the  sun- 
flower is  inherently  a  stalk  and  crude-fiber  crop,  while  corn  shows  a 
high  development  of  the  reproductive  function  and  is  inherently  a  grain 
crop.  Consequently  it  is  desirable  to  ensile  sunflowers  at  a  much  earlier 
stage  of  growth  than  corn,  since  it  is  a  general  fact  that  crude  fiber  de- 
creases in  digestibility  with  advance  in  growth,  with  an  accompanying 
decrease  in  the  palatability  of  the  crop  as  a  feed. 

Checks  upon  the  method  of  field  sampling  used  for. determining 
yield  and  composition  of  the  crop  were  obtained  by  weighing  and  samp- 
ling the  crop  at  harvest.  The  two  methods  are  in  general  agreement, 
except  that  the  crop  was  subjected  to  losses  of  moisture  enroute  from 
field  to  silo.  Such  losses  were  largely  prevented  in  the  field-sampling 
method. 

Sunflowers  produced  50  percent  more  dry  matter  per  acre  than  two 
fields  of  silage  corn  grown  near-by.  The  yields  of  ash,  crude  fiber,  and 
crude  fat  were  very  much  greater  in  the  sunflower  crop  than  yields  of 
these  substances  in  corn.  The  corn  crop,  however,  proved  superior  in 
production  of  nitrogen-free  extract. 

The  early  death  and  withering  of  the  lower  leaves  of  sunflowers 
is  considered  responsible  for  the  loss  of  nutrients,  altho  nutrients  from 
these  leaves  may  have  been  transferred  to  other  portions  of  the  plant. 

Results  of  digestibility  studies  conducted  with  silage  produced  in 
this  investigation  (Bulletin  253),  when  applied  to  the  field  data,  indicate 
no  marked  increase  in  yield  per  acre  of  digestible  nutrients  after  87  days 
from  the  planting  of  the  crop. 

The  sunflower  crop  removed  large  amounts  of  fertilizing  elements 
from  the  soil,  the  total  ash  amounting  to  900  pounds  per  acre.  The 
elements  present  in  largest  amount  in  the  crop  were,  in  the  order  of  their 
magnitude,  potassium,  calcium,  nitrogen,  magnesium,  sulfur,  and  phos- 
phorus. Aluminum  and  iron  were  present  in  samples  of  both  seed  and 


19251  THE  SUNFLOWER  AS  A  SILAGE  CROP  447 

stalk  in  appreciable  amounts,  altho  the  possibility  of  contamination  of 
the  samples  by  iron  during  their  preparation  for  analysis  was  not  pre- 
cluded. The  seeds  were  very  rich  in  potassium  and  nitrogen,  altho  they 
contained  less  than  6  percent  of  the  total  ash  of  the  crop. 

The  relative  proportions  of  the  ash  elements  in  the  seed  differed 
from  those  in  the  total  crop.  Marked  reductions  in  the  total  ash  in  the 
crop  occurred  toward  the  close  of  the  season. 

In  contrast  to  marked  changes  in  proportions  of  the  organic  con- 
stituents during  growth,  the  changes  in  the  relative  proportions  of  the 
ash  constituents  studied  were  much  less.  Aluminum  constituted  a 
rather  distinct  exception  to  this. 

Studies  of  the  effect  of  time  of  planting  upon  yield  and  composi- 
tion showed  very  pronounced  decreases  in  yield  due  to  late  planting, 
and  minor  effects  upon  the  composition  of  the  crop. 

REVIEW  OF  LITERATURE 
INVESTIGATIONS  DEALING  WITH  COMPOSITION  OR  YIELD  OF  SUNFLOWERS 

Amos  and  Woodman1  of  Cambridge  University,  England,  report 
yields  of  20  tons  of  sunflowers  containing  18.5  percent  of  dry  matter, 
while  maize  gave  yields  of  14  tons  containing  17  percent  of  dry  matter. 

Anthony  and  Henderson2  report  the  composition  of  sunflowers  at 
five  different  stages  of  growth.  Their  results  show  little  progressive 
change  in  composition  during  growth,  except  that  there  is  a  tendency 
for  a  decrease  in  carbohydrate  content  and  an  increase  in  fat  content. 
"Sunflower  silage  yielded  much  heavier  per  acre  than  corn  silage." 

Atkinson  and  Nelson,5  at  the  Montana  Station,  found  little  differ- 
ence between  the  yields  of  sunflowers  (reported  as  silage)  planted  April 
29  and  those  planted  May  29  and  June  4.  Rows  36  inches  apart  gave 
slightly  greater  yields  of  green  forage  than  those  planted  in  rows  8 
inches  apart,  and  nearly  double  the  yields  of  rows  42  inches  apart. 
Yields  of  dry  matter  are  not  reported. 

Bartlett7  compared  the  yields  of  Maine  field  corn,  red  clover,  and 
sunflower  heads,  finding  that  the  yields  of  dry  substance  were  4,224 
pounds,  3,400  pounds,  and  2,040  pounds  per  acre,  respectively.  The 
yields  of  fat  per  acre  in  the  three  crops  were  156  pounds,  133  pounds, 
and  317  pounds,  respectively. 

Blish8  determined  the  composition  of  sunflower  silage  produced 
from  sunflowers  ensiled  at  different  stages  of  growth.  "The  percent- 
ages of  food  constituents  do  not  differ  greatly  in  plants  of  various  stages 
of  maturity  up  to  the  point  where  seeds  are  formed  and  partially  hard- 
ened. With  advancing  maturity,  other  things  being  equal,  there  is  a 
slight  increase  in  dry  matter,  protein,  fiber,  and  digestible  carbohy- 
drates." 

The  Canada  Experimental  Farms11  report  yields  of  over  8  tons  of 
sunflower  heads  per  acre.  They  further  find  that  the  weight  of  the 


448  BULLETIN  No.  268  {.June, 

dry  matter  in  sunflower  heads  was  3,767  pounds  per  acre  when  the 
yield  of  sunflowers  (whole  plant)  was  7,219  pounds  of  dry  matter. 

Holden18  reports  a  greater  tonnage  of  sunflowers  than  silage  corn 
or  field  corn  at  the  Scottsbluff,  Nebraska,  Station. 

Jensen21  reports  the  yields  of  sunflowers  over  a  five-year  period, 
the  seed  having  been  sown  each  year  on  five  different  dates  at  one-week 
intervals.  While  there  was  considerable  variation  in  the  results,  the 
earliest  planted  sunflowers  tended  to  give  the  largest  yields  of  fresh 
matter. 

Jones,22  of  the  Oregon  Station,  reports  a  larger  tonnage  of  sun- 
flowers per  acre  over  a  series  of  years  than  either  oats  and  vetch  or  corn 
grown  for  silage. 

McHargue30  determined  the  amount  of  iron  in  seeds  by  the  col- 
orimetric  thiocyanate  method.  The  amount  of  iron  found  in  sunflower 
seeds  was  .0034  percent,  compared  to  .0039  percent  in  wheat,  .0050  in 
oats,  .0074  percent  in  soybeans  and  .0026  percent  in  yellow  corn. 

The  New  Hampshire  Station34  reports  sunflower  yields  40  percent 
larger  than  those  of  corn. 

Putnam,37  in  time-  and  rate-of-planting  experiments  in  northern 
Michigan,  found  that  plantings  of  May  26  gave  larger  yields  than 
plantings  of  June  2  and  June  9.  "Rowys  at  distances  of  24  to  36  inches 
gave  the  best  quality  of  silage."  "The  30-42  inch  rows  gave  the  heavi- 
est yields  and  also  required  less  seed  per  acre  for  a  stand  than  did  the 
closer  plantings." 

Quayle38  found  the  yield  per  acre  in  pounds  of  sunflowers  during 
1920  and  1921  to  be  50  percent  greater  than  corn.  » 

Quesenberry  et  al,39  at  the  New  Mexico  Station,  found  that  early 
plantings  (April  19)  "do  not  produce  as  heavy  a  tonnage  or  as  succu- 
lent plants  as  the  later  seedings." 

Schafer  and  Westley44  report  comparative  yields  of  2.35  tons  of  dry 
matter  per  acre  in  sunflowers  and  1.56  tons  in  corn  at  the  Washington 
Experiment  Station. 

Shaw  and  Wright46  report  the  composition  of  the  sunflower  plant  at 
seven  stages  of  growth  and  the  corn  plant  at  nine  stages.  Their  results 
show  that  when  these  two  plants  are  compared  upon  the  moisture-free 
basis,  they  are  similar  in  total  protein  and  albuminoid  protein,  but  that 
the  mature  sunflower  plant  contains  smaller  proportions  of  reducing 
sugars  and  non-reducing  sugars  than  the  corn  plant.  The  sunflower 
plant  contains  very  small  amounts  of  starch,  whereas  the  corn  plant 
beyond  the  "milk  stage"  contains  very  large  amounts.  Yields  of  the 
crops  are  not  included. 

Thatcher52  compared  the  yields  of  dry  matter  in  corn  and  sun- 
flowers grown  in  Ohio  for  silage.  The  yields  (fresh  basis)  of  sunflow- 
ers during  a  three-year  period  were  14.28  tons  per  acre,  while  for  corn 
the  yields  were  12.78  tons.  The  yield  of  dry  matter  in  the  sunflowers 


7925]  THE  SUNFLOWER  AS  A  SILAGE  CROP  449 

was  5,218  pounds,  compared  to  7,251  pounds  in  corn.  The  dry 
matter  of  the  sunflowers  contained  greater  proportions  of  protein, 
ether  extract,  fiber,  and  ash  than  that  of  the  corn,  and  the  yields  per 
acre  of  the  same  constituents,  with  the  exception  of  fiber,  were  also 
greater.  The  greatest  difference  in  composition  and  yield  was  with  the 
nitrogen-free  extract,  which  was  greater  for  corn. 

Vinall53  says:  "The  yields  of  sunflowers  have  been  consistently 
larger  than  those  of  corn  or  other  silage  crops  in  the  northern  part  of 
the  United  States  and  the  higher  altitudes  of  the  Rocky  Mountain 
region,  where  the  temperatures  are  low  during  the  summer  season." 

Zavitz56  reports  the  annual  average  yield  of  Mammoth  Russian 
sunflowers  in  tests  at  the  Ontario  Agricultural  College  from  1902  to 
1920,  inclusive,  to  have  been  5.6  tons  of  heads,  1,453  pounds  of  ripened 
seed,  and  18.2  tons  for  the  whole  crop. 

CROPS  OTHER  THAN  SUNFLOWER:  STUDIES  OF  COMPOSITION,  YIELD,  OR 
FEEDING  VALUE,  AT  DIFFERENT  STAGES  OF  GROWTH 

Corn 

Armsby4  determined  the  yields  and  digestibility  of  corn  harvested 
at  different  stages  of  growth  during  a  three-year  period.  He  found  in- 
creases of  200  to  300  percent  in  the  total  digestible  matter  per  acre  dur- 
ing the  interval  from  the  silking  stage  to  maturity,  and  increases  of  as 
much  as  37  percent  from  the  glazing  stage  to  maturity.  Yields  of  total 
digestible  matter  in  the  crop  ranged  from  4,000  to  6,500  pounds  per 
acre. 

Armsby,  Frear,  Caldwell,  and  Holter3  found  that  the  coefficients 
of  digestibility  of  fiber,  protein,  and  true  albuminoids  in  corn  fodder 
were  quite  constantly  depressed  as  the  corn  advanced  in  growth  and 
maturity.  Coefficients  for  fat  and  nitrogen-free  extract,  however,  in- 
creased somewhat  with  maturity. 

Babcock6  reported  analyses  of  samples  of  the  maize  plant  which 
show  increases  of  110  percent  in  percentage  of  dry  substance  in  the 
samples  of  plants  taken  during  the  period  August  18  to  September  23. 
The  dry  matter  showed  decreases  in  the  proportions  of  ash,  crude  pro- 
tein, and  crude  fiber,  but  a  distinct  increase  in  nitrogen-free  extract. 

Burrill  and  McCluer9  reported  yields  of  6,000  to  9,500  pounds  of 
dry  matter  per  acre  in  the  corn  crop.  Their  studies  of  the  composition 
of  the  dry  matter  of  the  ears,  stalks,  and  leaves  and  husk  portions  of 
the  plant  showed  that  the  ears  were  richest  in  crude  fat,  crude  protein, 
nitrogen-free  extract,  and  true  protein,  but  lowest  in  crude  fiber.  The 
leaves  and  husks  were  richest  in  crude  ash  and  poorest  in  nitrogen-free 
extract.  The  stalks  were  highest  in  crude  fiber,  and  poorest  in  crude 
fat,  crude  protein,  and  true  protein. 

Caldwell10  found  yields  of  6,000  to  7,500  pounds  of  dry  matter  per 
acre  in  the  mature  corn  crop,  of  which  the  ears  comprized  from  35  to 


450  BULLETIN  No.  268  [June, 

42  percent.  The  gains  in  total  dry  matter  per  acre  from  the  fully  tas- 
seled  stage  to  the  mature  stage  were  as  much  as  300  percent. 

Collier12  found  an  increase  of  about  13  percent  in  yield  of  dry 
matter  of  the  corn  plant  during  the  period  from  September  1 1  to  Sep- 
tember 29,  altho  total  protein  was  slightly  reduced  in  amount. 

Farrington16  followed  the  composition  of  the  dry  matter  of  the  corn 
plant  at  weekly  intervals  from  June  17  to  September  23.  Constant  and 
marked  decreases  in  percentages  of  ash  and  protein,  together  with  quite 
uniform  increase  of  nitrogen-free  extract  thruout  the  entire  period  were 
noted.  There  was  a  slight  decrease  in  the  proportion  of  crude  fiber. 

Frear17  determined  the  composition  and  yields  of  corn  at  different 
stages.  The  crude  protein  and  crude  ash  in  the  mature  plants  formed 
about  half  as  large  a  proportion  of  the  water-free  substance  as  they  did 
in  plants  three  to  four  feet  high.  Crude  fiber  was  also  somewhat  less, 
while  nitrogen-free  extract  showed  an  increase.  The  calculated  yields 
per  acre  of  total  digestible  organic  matter  on  August  2,  August  23,  and 
September  13  (mature  stage)  were  4,054  pounds,  5,287  pounds,  and 
8,636  pounds,  respectively.  • 

Hornberger  and  Raumer19  followed  the  growth  of  the  maize  plant 
from  June  18  to  September  10.  During  the  period  of  September  3 
to  September  10  there  was  a  small  decrease  in  the  dry  matter,  this  con- 
sisting of  losses  of  ash,  crude  protein,  and  crude  fiber.  The  starch, 
sugar,  etc.,  and  the  crude  fat  increased  during  the  same  period,  while 
the  amids  declined  30  percent. 

Ince20  reported  the  composition  and  yield  of  the  maize  plant  dur- 
ing the  later  stages  of  growth.  The  dry  matter  declined  in  its  pro- 
portions of  crude  protein  and  ash,  but  increased  in  crude  fat  and  car- 
bohydrates as  the  plant  approached  maturity.  The  yields  from  the 
"glazed"  to  the  "ripe"  stage  suffered  losses  of  total  dry  matter,  crude 
protein,  and  nitrogen-free  extract,  but  made  gains  in  crude  fat,  crude 
fiber,  and  ash.  The  ash  yields,  however,  were  decreased  in  two  of  the 
three  cases  studied. 

Jones  and  Huston23  determined  the  composition  of  maize  at  several 
different  stages  of  growth  and  reported  the  amount  of  certain  constitu- 
ents per  10,000  plants.  The  crop  suffered  some  losses  of  dry  matter, 
chiefly  total  ash  and  nitrogen-free  extract,  while  in  the  shock  from  Oc- 
tober 8  to  November  12,  but  lost  more  than  20  percent  of  all  constitu- 
ents except  fat  while  standing  in  the  field  during  the  same  period.  The 
greatest  loss  was  in  the  case  of  ash,  the  loss  being  over  40  percent." 

Jordan25  found  that  the  daily  rate  of  gain  of  dry  matter  in  the  corn 
crop  decreased  steadily  from  the  time  the  ears  were  beginning  to  form 
until  the  ears  were  glazed. 

"The  datg  of  Jones  and  Huston  have  been  used  in  Figs.  5-24  of  the  present 
bulletin  in  making  a  comparison  of  the  growth  of  the  corn  crop  with  that  of  sun- 
flowers. 


1925~\  THE  SUNFLOWER  AS  A  SILAGE  CROP  451 

Jordan,  Bartlett,  and  Merrill24  noted  rapid  increases  in  the  nitro- 
gen-free extract  content  of  the  corn  crop. 

Ladd28  reported  increases  in  the  yield  per  acre  of  the  several  con- 
stituents of  the  corn  crop  at  different  stages  of  growth. 

Latshaw  and  Miller29  estimated  the  "weight  in  pounds  of  the  ele- 
ments removed  per  acre  from  the  air  and  soil  by  6,200  Pride  of  Saline 
corn  plants  grown  at  Manhattan,  Kansas,  in  1920."  The  estimated 
amounts  of  some  of  the  elements  were:  nitrogen,  156  pounds;  phos- 
phorus, 22  pounds;  potassium,  101  pounds;  calcium,  21  pounds;  mag- 
nesium, 19  pounds;  sulfur,  17  pounds;  iron,  5  pounds;  and  aluminum, 
4  pounds. 

Morrow  and  Gardner,31  from  results  of  field  experiments  with  corn, 
state  that  "while  there  has  been  a  fairly  uniform  increase  in  the  weight 
of  the  ash,  protein,  fiber,  nitrogen-free  extract,  and  the  fat  or  ether  ex- 
tract up  to  the  date  when  the  corn  was  fairly  well  matured,  the  compo- 
sition of  the  dry  matter  shows  a  steady  decrease  in  the  percentage  of 
ash  and  protein;  at  first  there  is  an  increase  and  then  a  decrease  in  the 
percentage  of  fiber;  a  steady  increase  in  the  percentage  of  nitrogen-free 
extract,  and  a  good  deal  of  variation  in  the  percentage  of  ether  extract, 
with,  in  general,  a  considerable  decrease  until  the  plant  becomes  nearly 
mature." 

Morse32  observed  steady  decreases  of  ash,  protein,  and  fiber,  but 
increases  of  soluble  carbohydrates  and  fat  in  the  dry  matter  of  corn  at 
different  stages  of  growth. 

Roberts  and  Clinton41  report  continuous  increases  in  the  yields  of 
all  constituents  of  the  corn  crop  from  bloom  to  maturity. 

Roberts  and  Wing42  report  results  similar  to  those  of  Roberts  and 
Clinton. 

Schweitzer45  studied  dry  matter  and  ash  contents  of  corn  at  four- 
teen successive  stages.  Dry  matter  continued  to  increase  in  amount  in 
the  entire  plant,  altho  there  was  a  decline  of  dry  matter  in  the  stalk 
during  the  last  periods.  The  ash  of  the  entire  plant  decreased  slightly 
during  the  last  period,  this  decrease  being  caused  entirely  by  falling  off 
in  the  stalk,  as  the  ear  suffered  no  losses. 

Shelton,47  in  studies  of  the  composition  of  corn  at  different  stages 
of  growth,  found  that  with  one  exception  the  fat  and  nitrogen-free 
extract  increased  proportionally  as  the  grain  developed,  while  the  fiber, 
ash,  and  nitrogenous  materials  decreased. 

Short48  reports  losses  in  fodder  corn,  due  to  weathering,  of  13  to 
23  percent  of  the  dry  matter  and  60  to  72  percent  of  the  protein. 

Shutt49  studied  the  composition  of  different  varieties  of  corn  dur- 
ing growth  and  reported  decreases  in  the  proportions  of  the  dry  matter 
made  up  by  ash,  protein,  and  fiber,  with  increases  of  "nitrogen-free  ex- 
tract and  fluctuations  in  the  ether  extract." 

Smith50  found  increased  yields  per  acre  of  all  constituents  of  the 
dry  matter  from  the  tasseling  to  the  ripe  stage,  but  the  proportions  of 


452  BULLETIN  No.  268  [/««<?, 

the  dry  matter  formed  by  protein,  crude  fiber,  and  ash  declined,  while 
the  proportions  of  fat  and  nitrogen-free  extract  increased. 

Whitcher54  found  increases  in  the  yield  of  dry  matter  per  acre, 
during  ten-,  fourteen-,  and  twenty-eight  day  periods,  of  217  percent,  66 
percent,  and  30  percent,  respectively,  for  each  period  over  the  preceding 
one. 

Miscellaneous  Crops 

Deherain  and  Meyer's14  studies  of  the  development  of  wheat  show 
that  losses  of  all  constituents  of  the  entire  plant  (excluding  roots)  in- 
cluded in  their  determinations,  with  the  exception  of  cane  sugar,  suffered 
losses  following  the  time  of  harvest.  The  greatest  percentage  loss  was 
in  the  case  of  glucose,  both  glucose  and  cane  sugar  disappearing  from 
the  stems.  The  grain  suffered  some  loss,  but  not  so  much  as  the  stems. 

Failyer  and  Willard,15  in  studies  of  the  composition  of  kaffir-corn 
fodder  and  grain,  found  that  during  the  changes  from  the  early  stages 
of  seed  formation  to  maturity  of  the  seed,  crude  protein,  ash,  and  al- 
buminoid nitrogen  formed  decreasing  proportions  of  the  dry  substance 
of  the  fodder,  while  crude  fiber  remained  practically  constant  and  nitro- 
gen-free extract  increased. 

Frear17  found  decreases  of  ash  and  protein  in  the  dry  matter  of 
clover  and  of  oats,  and  also  fat  in  the  case  of  clover,  as  the  plants 
develop.  Both  fiber  and  nitrogen-free  extract  formed  increasing  per- 
centages. 

Nedokutschajew33  observed  the  changes  of  nitrogenous  substances 
in  cereals  during  ripening.  The  total  nitrogen  formed  decreasing  pro- 
portions of  the  dry  substance  of  rye  and  wheat  during  ripening,  but  in- 
creasing or  variable  proportions  in  barley  and  oats.  The  proportions 
of  amid  nitrogen  and  asparagin  nitrogen  decreased  continually  in  all 
four  cereals. 

Snyder51  noted  that  ash  and  crude  protein  formed  decreasing  per- 
centages of  the  dry  matter  'of  sorghum  in  samples  taken  at  intervals 
from  August  18  to  September  26. 

Widtsoe55  made  exhaustive  studies  of  the  composition  and  yield  of 
lucern  during  a  period  of  four  months.  The  yields  of  dry  matter  be- 
came continually  greater  from  May  4  to  July  27,  when  the  maximum 
was  reached,  and  then  fell  off  until  August  24,  the  final  sampling  date. 
The  yields  of  crude  fiber  and  nitrogen-free  extract  were  similar  to  total 
dry  matter  in  their  relationships,  but  crude  protein,  crude  ash,  and 
crude  fat  reached  their  maximum  three  to  four  weeks  earlier.  The 
crude  fiber  was  the  only  constituent  of  the  dry  matter  which  did  not  de- 
crease in  amount  after  reaching  the  maximum.  Crude  protein  and 
crude  ash  suffered  the  greatest  losses. 


1925~\  THE  SUNFLOWER  AS  A  SILAGE  CROP  453 

CONCLUSIONS  FROM  REVIEW  OF  LITERATURE 

The  composition  and  the  yields  of  various  silage  and  forage  crops 
have  been  studied  by  many  investigators.  Very  few  of  these  studies 
embraced  yields  of  nutrients  in  the  sunflower  crop  at  different  stages 
of  growth,  altho  such  data  for  the  corn  crop  are  quite  abundant.  The 
yields  of  sunflowers  compared  with  those  of  other  crops  that  are  re- 
ported in  terms  of  fresh  matter  are  somewhat  misleading  on  account  of 
differences  in  moisture  content.  The  yields  of  sunflowers  on  the  fresh- 
matter  basis  have  usually  been  greater  than  those  of  corn  grown  under 
the  same  conditions,  but  in  some  cases  the  yields  of  dry  matter  of  the 
corn  crop  have  been  greater. 

It  is  evident  that  the  sunflower  may  be  grown  under  a  wide  range 
of  climatic  conditions,  experiments  having  been  conducted  in  New 
Hampshire,  Oregon,  New  Mexico,  and  Canada.  Differences  in  results 
obtained  in  experiments  in  which  studies  were  made  of  the  time  and 
rate  of  planting  and  time  of  harvesting  are  doubtless  to  be  attributed 
largely  to  differences  existing  between  the  regions  in  which  the  crops 
were  grown. 

The  extensive  studies  of  the  composition  of  the  corn  plant  con- 
ducted at  American  experiment  stations  indicate  that  the  development 
of  the  nutrients  in  the  corn  crop  follows  a  well-defined  path,  and  when 
this  is  compared  to  the  development  of  nutrients  in  the  sunflower  crop, 
as  shown  in  the  investigation  here  reported,  distinct  differences  be- 
tween the  crops  are  apparent. 

Corn  and  miscellaneous  crops,  such  as  wheat,  clover,  oats,  rye,  sorg- 
hum, etc.,  exhibit  some  changes  in  the  composition  of  their  dry  matter, 
when  maturing,  similar  to  those  found  in  sunflowers.  Among  these 
the  most  pronounced  are  decreases  in  the  proportions  of  crude  protein 
and  ash.  The  nitrogen-free  extract  in  the  dry  matter  of  these  crops 
differs  markedly  from  that  in  sunflowers,  for  in  corn  and  the  miscel- 
laneous crops  mentioned,  nitrogen-free  extract  increases  rapidly  at 
maturity  while  in  sunflowers  it  decreases. 

Losses  of  nutrients  occurred  in  corn  and  some  other  crops  follow- 
ing maturity,  and  in  cases  in  which  the  crop  was  exposed  to  the  weather 
following  harvest,  the  losses  of  certain  nutrients  were  extensive.  These 
losses  consisted  chiefly  of  ash  and  crude  protein,  and  were  usually  least 
in  the  case  of  crude  fiber.  Such  phenomena  are  in  general  harmony 
with  the  results  of  the  studies  of  the  sunflower  crop  herewith  reported. 


454  BULLETIN  No.  268  [June, 

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